diff --git a/client/src/pages/project-detail/item-image-gallery-overlay.tsx b/client/src/pages/project-detail/item-image-gallery-overlay.tsx
new file mode 100644
index 0000000..59ef980
--- /dev/null
+++ b/client/src/pages/project-detail/item-image-gallery-overlay.tsx
@@ -0,0 +1,151 @@
+import { useEffect, useRef } from 'react';
+import { ChevronLeft, ChevronRight, X } from 'lucide-react';
+
+export interface GalleryImage {
+  id: string;
+  url: string;
+}
+
+interface ItemImageGalleryOverlayProps {
+  isOpen: boolean;
+  itemName: string;
+  images: GalleryImage[];
+  activeIndex: number;
+  isLoading: boolean;
+  error: string | null;
+  onClose: () => void;
+  onNext: () => void;
+  onPrevious: () => void;
+}
+
+export function ItemImageGalleryOverlay({
+  isOpen,
+  itemName,
+  images,
+  activeIndex,
+  isLoading,
+  error,
+  onClose,
+  onNext,
+  onPrevious
+}: ItemImageGalleryOverlayProps) {
+  const closeButtonRef = useRef<HTMLButtonElement | null>(null);
+
+  useEffect(() => {
+    if (!isOpen) {
+      return;
+    }
+
+    const handleKeyDown = (event: KeyboardEvent) => {
+      if (event.key === 'Escape') {
+        event.preventDefault();
+        onClose();
+        return;
+      }
+
+      if (isLoading || images.length <= 1) {
+        return;
+      }
+
+      if (event.key === 'ArrowRight') {
+        event.preventDefault();
+        onNext();
+      } else if (event.key === 'ArrowLeft') {
+        event.preventDefault();
+        onPrevious();
+      }
+    };
+
+    window.addEventListener('keydown', handleKeyDown);
+    return () => window.removeEventListener('keydown', handleKeyDown);
+  }, [isOpen, onClose, onNext, onPrevious, images.length, isLoading]);
+
+  useEffect(() => {
+    if (isOpen) {
+      closeButtonRef.current?.focus();
+    }
+  }, [isOpen]);
+
+  if (!isOpen) {
+    return null;
+  }
+
+  const activeImage = images[activeIndex] ?? null;
+
+  return (
+    <div
+      className="fixed inset-0 z-50 flex items-center justify-center bg-slate-900/80 px-4 py-8"
+      role="dialog"
+      aria-modal="true"
+      aria-label={`Image gallery for ${itemName}`}
+      onClick={onClose}
+    >
+      <div
+        className="relative flex w-full max-w-4xl flex-col gap-4 rounded-2xl bg-white p-6 shadow-xl"
+        onClick={(event) => event.stopPropagation()}
+      >
+        <div className="flex items-start justify-between gap-4">
+          <div>
+            <h2 className="text-lg font-semibold text-slate-900">{itemName}</h2>
+            <p className="text-sm text-slate-500">
+              {images.length > 0 ? `Image ${activeIndex + 1} of ${images.length}` : 'No images available'}
+            </p>
+          </div>
+          <button
+            ref={closeButtonRef}
+            type="button"
+            onClick={onClose}
+            className="inline-flex h-10 w-10 items-center justify-center rounded-full border border-slate-200 bg-white text-slate-600 transition hover:text-slate-900 focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white"
+            title="Close gallery"
+          >
+            <X aria-hidden className="h-5 w-5" />
+            <span className="sr-only">Close gallery</span>
+          </button>
+        </div>
+
+        <div className="relative flex min-h-[320px] items-center justify-center overflow-hidden rounded-xl bg-slate-100">
+          {isLoading ? (
+            <p className="text-sm text-slate-500">Loading images…</p>
+          ) : error ? (
+            <p className="px-4 text-center text-sm font-medium text-red-600">{error}</p>
+          ) : activeImage ? (
+            <>
+              <img
+                key={activeImage.id}
+                src={activeImage.url}
+                alt={`Image ${activeIndex + 1} of ${itemName}`}
+                className="max-h-[70vh] w-full object-contain"
+              />
+              {images.length > 1 ? (
+                <>
+                  <button
+                    type="button"
+                    onClick={onPrevious}
+                    className="absolute left-4 top-1/2 -translate-y-1/2 rounded-full bg-white/90 p-2 text-slate-700 shadow transition hover:bg-white focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white"
+                    title="Previous image"
+                  >
+                    <ChevronLeft aria-hidden className="h-5 w-5" />
+                    <span className="sr-only">Previous image</span>
+                  </button>
+                  <button
+                    type="button"
+                    onClick={onNext}
+                    className="absolute right-4 top-1/2 -translate-y-1/2 rounded-full bg-white/90 p-2 text-slate-700 shadow transition hover:bg-white focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white"
+                    title="Next image"
+                  >
+                    <ChevronRight aria-hidden className="h-5 w-5" />
+                    <span className="sr-only">Next image</span>
+                  </button>
+                </>
+              ) : null}
+            </>
+          ) : (
+            <p className="px-4 text-center text-sm text-slate-500">
+              No images have been added for this item yet.
+            </p>
+          )}
+        </div>
+      </div>
+    </div>
+  );
+}
diff --git a/client/src/pages/project-detail/item-thumbnail.tsx b/client/src/pages/project-detail/item-thumbnail.tsx
index 706f9f4..b91f62c 100644
--- a/client/src/pages/project-detail/item-thumbnail.tsx
+++ b/client/src/pages/project-detail/item-thumbnail.tsx
@@ -4,6 +4,7 @@ interface ItemThumbnailProps {
   url: string | null;
   alt: string;
   size?: 'sm' | 'md';
+  onClick?: () => void;
 }
 
 const sizeClassMap: Record<Required<ItemThumbnailProps>['size'], string> = {
@@ -11,28 +12,40 @@ const sizeClassMap: Record<Required<ItemThumbnailProps>['size'], string> = {
   md: 'h-20 w-20'
 };
 
-export function ItemThumbnail({ url, alt, size = 'sm' }: ItemThumbnailProps) {
+export function ItemThumbnail({ url, alt, size = 'sm', onClick }: ItemThumbnailProps) {
   const [hasError, setHasError] = useState(false);
   const hasImage = !!url && !hasError;
   const sizeClasses = sizeClassMap[size];
+  const containerClasses = `flex-shrink-0 overflow-hidden rounded-md border border-slate-200 bg-slate-100 ${sizeClasses} ${
+    onClick ? 'cursor-pointer transition hover:border-blue-200 hover:shadow focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white' : ''
+  }`;
 
-  return (
-    <div
-      className={`flex-shrink-0 overflow-hidden rounded-md border border-slate-200 bg-slate-100 ${sizeClasses}`}
-    >
-      {hasImage ? (
-        <img
-          src={url ?? ''}
-          alt={alt}
-          className="h-full w-full object-cover"
-          loading="lazy"
-          onError={() => setHasError(true)}
-        />
-      ) : (
-        <div className="flex h-full w-full items-center justify-center px-2 text-center text-[0.625rem] font-medium uppercase tracking-wide text-slate-400">
-          No Image
-        </div>
-      )}
+  const content = hasImage ? (
+    <img
+      src={url ?? ''}
+      alt={alt}
+      className="h-full w-full object-cover"
+      loading="lazy"
+      onError={() => setHasError(true)}
+    />
+  ) : (
+    <div className="flex h-full w-full items-center justify-center px-2 text-center text-[0.625rem] font-medium uppercase tracking-wide text-slate-400">
+      No Image
     </div>
   );
+
+  if (onClick) {
+    return (
+      <button
+        type="button"
+        onClick={onClick}
+        className={containerClasses}
+        aria-label={`View images for ${alt}`}
+      >
+        {content}
+      </button>
+    );
+  }
+
+  return <div className={containerClasses}>{content}</div>;
 }
diff --git a/client/src/pages/project-detail/project-detail-page.tsx b/client/src/pages/project-detail/project-detail-page.tsx
index 43462f9..5e52954 100644
--- a/client/src/pages/project-detail/project-detail-page.tsx
+++ b/client/src/pages/project-detail/project-detail-page.tsx
@@ -1,4 +1,4 @@
-import { useMemo, useRef, useState } from 'react';
+import { useCallback, useMemo, useRef, useState } from 'react';
 import { useParams } from 'react-router-dom';
 import type { Item } from '@shared/models/item';
 import { useQueryClient } from '@tanstack/react-query';
@@ -22,6 +22,7 @@ import { ProjectHeader } from './project-header';
 import { ProjectDescriptionSection } from './project-description-section';
 import { TrackedAttributesSection } from './tracked-attributes-section';
 import { ProjectItemsSection } from './project-items-section';
+import { ItemImageGalleryOverlay, type GalleryImage } from './item-image-gallery-overlay';
 
 export function ProjectDetailPage() {
   const { projectId } = useParams<{ projectId: string }>();
@@ -47,6 +48,16 @@ export function ProjectDetailPage() {
   const [isLoadingItemDetails, setIsLoadingItemDetails] = useState(false);
   const [editItemError, setEditItemError] = useState<string | null>(null);
   const [isSavingItem, setIsSavingItem] = useState(false);
+  const [isGalleryOpen, setIsGalleryOpen] = useState(false);
+  const [galleryItemName, setGalleryItemName] = useState('');
+  const [galleryImages, setGalleryImages] = useState<GalleryImage[]>([]);
+  const [galleryActiveIndex, setGalleryActiveIndex] = useState(0);
+  const [isGalleryLoading, setIsGalleryLoading] = useState(false);
+  const [galleryError, setGalleryError] = useState<string | null>(null);
+  const galleryCacheRef = useRef(
+    new Map<string, { images: GalleryImage[]; defaultImageId: string | null }>()
+  );
+  const galleryRequestIdRef = useRef(0);
 
   const project = projectQuery.data;
   const items = useMemo(() => itemsQuery.data?.data ?? [], [itemsQuery.data]);
@@ -79,6 +90,126 @@ export function ProjectDetailPage() {
     return Array.from(attributeSet).sort((a, b) => a.localeCompare(b));
   }, [projectAttributes, items]);
 
+  const handleViewItemImages = useCallback(
+    async (item: Item) => {
+      const displayName = item.manufacturer ? `${item.manufacturer} ${item.model}` : item.model;
+
+      galleryRequestIdRef.current += 1;
+      const requestId = galleryRequestIdRef.current;
+
+      const cached = galleryCacheRef.current.get(item.id);
+      const fallbackImages =
+        item.images && item.images.length
+          ? item.images.map((image) => ({ id: image.id, url: image.url }))
+          : [];
+
+      let initialImages = cached?.images ?? fallbackImages;
+
+      if (!initialImages.length && item.defaultImageUrl) {
+        initialImages = [
+          {
+            id: item.defaultImageId ?? 'default-image',
+            url: item.defaultImageUrl
+          }
+        ];
+      }
+
+      const initialDefaultId = cached?.defaultImageId ?? item.defaultImageId ?? null;
+
+      setIsGalleryOpen(true);
+      setGalleryItemName(displayName);
+      setGalleryError(null);
+      setGalleryImages(initialImages);
+      setIsGalleryLoading(!cached && initialImages.length === 0);
+
+      if (initialImages.length) {
+        if (initialDefaultId) {
+          const defaultIndex = initialImages.findIndex((image) => image.id === initialDefaultId);
+          setGalleryActiveIndex(defaultIndex >= 0 ? defaultIndex : 0);
+        } else {
+          setGalleryActiveIndex(0);
+        }
+      } else {
+        setGalleryActiveIndex(0);
+      }
+
+      if (cached) {
+        return;
+      }
+
+      try {
+        const fullItem = await fetchItem(item.id);
+        if (galleryRequestIdRef.current !== requestId) {
+          return;
+        }
+
+        const normalizedImages =
+          fullItem.images?.map((image) => ({
+            id: image.id,
+            url: image.url
+          })) ?? [];
+        const defaultId = fullItem.defaultImageId ?? null;
+
+        galleryCacheRef.current.set(item.id, {
+          images: normalizedImages,
+          defaultImageId: defaultId
+        });
+
+        setGalleryImages(normalizedImages);
+
+        if (normalizedImages.length) {
+          const resolvedIndex = defaultId
+            ? normalizedImages.findIndex((image) => image.id === defaultId)
+            : -1;
+          setGalleryActiveIndex(resolvedIndex >= 0 ? resolvedIndex : 0);
+        } else {
+          setGalleryActiveIndex(0);
+        }
+        setGalleryError(null);
+      } catch (error) {
+        if (galleryRequestIdRef.current !== requestId) {
+          return;
+        }
+
+        const message =
+          error instanceof Error && error.message.trim().length
+            ? error.message.trim()
+            : 'Failed to load item images.';
+        setGalleryError(message);
+      } finally {
+        if (galleryRequestIdRef.current === requestId) {
+          setIsGalleryLoading(false);
+        }
+      }
+    },
+    []
+  );
+
+  const handleCloseGallery = useCallback(() => {
+    galleryRequestIdRef.current += 1;
+    setIsGalleryOpen(false);
+    setIsGalleryLoading(false);
+    setGalleryError(null);
+  }, []);
+
+  const handleGalleryNext = useCallback(() => {
+    setGalleryActiveIndex((current) => {
+      if (galleryImages.length <= 1) {
+        return current;
+      }
+      return (current + 1) % galleryImages.length;
+    });
+  }, [galleryImages]);
+
+  const handleGalleryPrevious = useCallback(() => {
+    setGalleryActiveIndex((current) => {
+      if (galleryImages.length <= 1) {
+        return current;
+      }
+      return (current - 1 + galleryImages.length) % galleryImages.length;
+    });
+  }, [galleryImages]);
+
   const openItemModal = (mode: 'url' | 'manual' | 'edit', initialUrl: string | null) => {
     setItemModalMode(mode);
     setModalInitialUrl(initialUrl);
@@ -467,6 +598,7 @@ export function ProjectDetailPage() {
         isImportingFromUrl={isImportingItem}
         onEditItem={handleEditItem}
         projectId={projectId}
+        onViewItemImages={handleViewItemImages}
       />
 
       <ItemFormModal
@@ -482,6 +614,18 @@ export function ProjectDetailPage() {
         isInitialDataLoading={itemModalInitialDataLoading}
         initialDataError={itemModalInitialDataError}
       />
+
+      <ItemImageGalleryOverlay
+        isOpen={isGalleryOpen}
+        itemName={galleryItemName}
+        images={galleryImages}
+        activeIndex={galleryActiveIndex}
+        isLoading={isGalleryLoading}
+        error={galleryError}
+        onClose={handleCloseGallery}
+        onNext={handleGalleryNext}
+        onPrevious={handleGalleryPrevious}
+      />
     </div>
   );
 }
diff --git a/client/src/pages/project-detail/project-items-desktop-table.tsx b/client/src/pages/project-detail/project-items-desktop-table.tsx
index 19ef675..b7fe815 100644
--- a/client/src/pages/project-detail/project-items-desktop-table.tsx
+++ b/client/src/pages/project-detail/project-items-desktop-table.tsx
@@ -12,6 +12,7 @@ interface ProjectItemsDesktopTableProps {
   onTogglePrices: (itemId: string) => void;
   onEditItem: (item: Item) => void;
   projectId: string | undefined;
+  onViewItemImages: (item: Item) => void;
 }
 
 export function ProjectItemsDesktopTable({
@@ -20,7 +21,8 @@ export function ProjectItemsDesktopTable({
   expandedItemId,
   onTogglePrices,
   onEditItem,
-  projectId
+  projectId,
+  onViewItemImages
 }: ProjectItemsDesktopTableProps) {
   return (
     <div className="hidden md:block">
@@ -59,38 +61,43 @@ export function ProjectItemsDesktopTable({
                   <tr className={`hover:bg-slate-50 ${isExpanded ? 'bg-slate-50' : ''}`}>
                     <td className="px-4 py-3 align-top">
                       <div className="flex items-start gap-3">
-                        <ItemThumbnail url={item.defaultImageUrl} alt={displayName} size="sm" />
+                        <ItemThumbnail
+                          url={item.defaultImageUrl}
+                          alt={displayName}
+                          size="sm"
+                          onClick={() => onViewItemImages(item)}
+                        />
                         <div className="flex flex-1 flex-col gap-1">
                           <div className="flex items-center gap-2">
-                          <button
-                            type="button"
-                            onClick={() => onEditItem(item)}
-                            className="group inline-flex items-center gap-2 rounded-md text-left text-slate-900 transition hover:text-blue-600 focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white"
-                            title="Edit item details"
-                          >
-                            <span
-                              aria-hidden
-                              className={`inline-block h-2.5 w-2.5 rounded-full ${
-                                item.status === 'active' ? 'bg-emerald-500' : 'bg-slate-300'
-                              }`}
-                            />
-                            <span className="font-semibold group-hover:underline">
-                              {displayName}
-                            </span>
-                          </button>
-                          {item.sourceUrl ? (
-                            <a
-                              href={item.sourceUrl}
-                              target="_blank"
-                              rel="noreferrer"
-                              className="inline-flex h-8 w-8 items-center justify-center rounded-md text-blue-600 transition focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white"
-                              title="Open source link"
+                            <button
+                              type="button"
+                              onClick={() => onEditItem(item)}
+                              className="group inline-flex items-center gap-2 rounded-md text-left text-slate-900 transition hover:text-blue-600 focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white"
+                              title="Edit item details"
                             >
-                              <ExternalLink aria-hidden className="h-4 w-4" />
-                              <span className="sr-only">Open source link</span>
-                            </a>
-                          ) : null}
-                        </div>
+                              <span
+                                aria-hidden
+                                className={`inline-block h-2.5 w-2.5 rounded-full ${
+                                  item.status === 'active' ? 'bg-emerald-500' : 'bg-slate-300'
+                                }`}
+                              />
+                              <span className="font-semibold group-hover:underline">
+                                {displayName}
+                              </span>
+                            </button>
+                            {item.sourceUrl ? (
+                              <a
+                                href={item.sourceUrl}
+                                target="_blank"
+                                rel="noreferrer"
+                                className="inline-flex h-8 w-8 items-center justify-center rounded-md text-blue-600 transition focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2 focus-visible:ring-offset-white"
+                                title="Open source link"
+                              >
+                                <ExternalLink aria-hidden className="h-4 w-4" />
+                                <span className="sr-only">Open source link</span>
+                              </a>
+                            ) : null}
+                          </div>
                           {item.note ? (
                             <span className="text-xs text-slate-500">{item.note}</span>
                           ) : null}
diff --git a/client/src/pages/project-detail/project-items-mobile-list.tsx b/client/src/pages/project-detail/project-items-mobile-list.tsx
index 8a8473a..5f84da0 100644
--- a/client/src/pages/project-detail/project-items-mobile-list.tsx
+++ b/client/src/pages/project-detail/project-items-mobile-list.tsx
@@ -11,6 +11,7 @@ interface ProjectItemsMobileListProps {
   onTogglePrices: (itemId: string) => void;
   onEditItem: (item: Item) => void;
   projectId: string | undefined;
+  onViewItemImages: (item: Item) => void;
 }
 
 export function ProjectItemsMobileList({
@@ -19,7 +20,8 @@ export function ProjectItemsMobileList({
   expandedItemId,
   onTogglePrices,
   onEditItem,
-  projectId
+  projectId,
+  onViewItemImages
 }: ProjectItemsMobileListProps) {
   return (
     <div className="space-y-4 md:hidden">
@@ -33,7 +35,12 @@ export function ProjectItemsMobileList({
         return (
           <div key={item.id} className="rounded-xl border border-slate-200 p-4 shadow-sm">
             <div className="flex items-start gap-4">
-              <ItemThumbnail url={item.defaultImageUrl} alt={displayName} size="md" />
+              <ItemThumbnail
+                url={item.defaultImageUrl}
+                alt={displayName}
+                size="md"
+                onClick={() => onViewItemImages(item)}
+              />
               <div className="flex flex-1 flex-col gap-2">
                 <div className="flex items-start gap-2">
                   <button
diff --git a/client/src/pages/project-detail/project-items-section.tsx b/client/src/pages/project-detail/project-items-section.tsx
index 7931c1a..6484aed 100644
--- a/client/src/pages/project-detail/project-items-section.tsx
+++ b/client/src/pages/project-detail/project-items-section.tsx
@@ -19,6 +19,7 @@ interface ProjectItemsSectionProps {
   isImportingFromUrl: boolean;
   onEditItem: (item: Item) => void;
   projectId: string | undefined;
+  onViewItemImages: (item: Item) => void;
 }
 
 export function ProjectItemsSection({
@@ -33,7 +34,8 @@ export function ProjectItemsSection({
   onAddManual,
   isImportingFromUrl,
   onEditItem,
-  projectId
+  projectId,
+  onViewItemImages
 }: ProjectItemsSectionProps) {
   const [showDifferencesOnly, setShowDifferencesOnly] = useState(false);
   const [expandedItemId, setExpandedItemId] = useState<string | null>(null);
@@ -134,6 +136,7 @@ export function ProjectItemsSection({
           onTogglePrices={handleTogglePrices}
           onEditItem={onEditItem}
           projectId={projectId}
+          onViewItemImages={onViewItemImages}
         />
 
         <ProjectItemsMobileList
@@ -143,6 +146,7 @@ export function ProjectItemsSection({
           onTogglePrices={handleTogglePrices}
           onEditItem={onEditItem}
           projectId={projectId}
+          onViewItemImages={onViewItemImages}
         />
       </section>