diff --git a/frontend/src/api/syntheses.ts b/frontend/src/api/syntheses.ts
index caba9f3..e8fb545 100644
--- a/frontend/src/api/syntheses.ts
+++ b/frontend/src/api/syntheses.ts
@@ -74,8 +74,8 @@ export const synthesesApi = {
     api.delete<void>(`/syntheses/${id}`),
 
   /** POST /syntheses/generate -- kick off an async generation job, returns a job ID. */
-  generate: (): Promise<GenerateResponse> =>
-    api.post<GenerateResponse>('/syntheses/generate'),
+  generate: (themeId: string): Promise<GenerateResponse> =>
+    api.post<GenerateResponse>('/syntheses/generate', { theme_id: themeId }),
 
   /** Build the SSE endpoint URL for streaming generation progress. */
   progressUrl: (jobId: string): string =>
diff --git a/frontend/src/i18n/fr.ts b/frontend/src/i18n/fr.ts
index 0ceb468..e8d1a19 100644
--- a/frontend/src/i18n/fr.ts
+++ b/frontend/src/i18n/fr.ts
@@ -83,6 +83,9 @@ const fr = {
   'generate.model': 'Modele',
   'generate.noWebSearchWarning':
     'Le fournisseur selectionne ne supporte pas la recherche web. Les resultats seront bases uniquement sur les connaissances du modele.',
+  'generate.selectTheme': 'Theme a generer',
+  'generate.noThemes': 'Aucun theme configure. Creez un theme pour pouvoir generer une synthese.',
+  'generate.createThemeLink': 'Creer un theme',
 
   // Synthesis Detail
   'synthesis.title': 'Synthese de la Semaine {week}',
diff --git a/frontend/src/pages/GenerateSynthesis.tsx b/frontend/src/pages/GenerateSynthesis.tsx
index 7781869..7a28776 100644
--- a/frontend/src/pages/GenerateSynthesis.tsx
+++ b/frontend/src/pages/GenerateSynthesis.tsx
@@ -7,12 +7,13 @@ import {
   Show,
   For,
 } from 'solid-js';
-import { useNavigate } from '@solidjs/router';
+import { useNavigate, A } from '@solidjs/router';
 import { AlertCircle, AlertTriangle, CheckCircle, Circle, Loader2 } from 'lucide-solid';
 import { useI18n } from '~/i18n';
 import { synthesesApi } from '~/api/syntheses';
 import { settingsApi } from '~/api/settings';
 import { configApi } from '~/api/config';
+import { themesApi, type ThemeResponse } from '~/api/themes';
 import { isApiError, DEFAULT_SETTINGS } from '~/types';
 import type { UserSettings, ProviderConfig, ProgressEvent } from '~/types';
 import { createSSEConnection, type SSEConnection, type SSEStatus } from '~/utils/sse';
@@ -52,6 +53,8 @@ const GenerateSynthesis: Component = () => {
 
   const [settings, setSettings] = createSignal<UserSettings>({ ...DEFAULT_SETTINGS });
   const [providers, setProviders] = createSignal<ProviderConfig[]>([]);
+  const [themes, setThemes] = createSignal<ThemeResponse[]>([]);
+  const [selectedThemeId, setSelectedThemeId] = createSignal<string>('');
   const [loadingSettings, setLoadingSettings] = createSignal(true);
   const [generating, setGenerating] = createSignal(false);
   const [error, setError] = createSignal<string | null>(null);
@@ -60,15 +63,20 @@ const GenerateSynthesis: Component = () => {
 
   onMount(async () => {
     try {
-      const [data, providerList] = await Promise.all([
+      const [data, providerList, themeList] = await Promise.all([
         settingsApi.get().catch((err) => {
           if (isApiError(err) && err.status === 404) return null;
           throw err;
         }),
         configApi.listProviders().catch(() => [] as ProviderConfig[]),
+        themesApi.list().catch(() => [] as ThemeResponse[]),
       ]);
       if (data) setSettings(data);
       setProviders(providerList);
+      setThemes(themeList);
+      if (themeList.length > 0) {
+        setSelectedThemeId(themeList[0].id);
+      }
     } catch {
       // Non-404 settings error — use defaults silently
     } finally {
@@ -210,7 +218,7 @@ const GenerateSynthesis: Component = () => {
     setSuccess(false);
 
     try {
-      const response = await synthesesApi.generate();
+      const response = await synthesesApi.generate(selectedThemeId());
       const url = synthesesApi.progressUrl(response.job_id);
       const conn = createSSEConnection(url);
       setSSEConnection(conn);
@@ -264,6 +272,39 @@ const GenerateSynthesis: Component = () => {
               </p>
             </div>
 
+            {/* Theme selection */}
+            <Show
+              when={themes().length > 0}
+              fallback={
+                <div class="mt-4 bg-yellow-50 border border-yellow-200 rounded-md p-4">
+                  <p class="text-sm text-yellow-800">
+                    {t('generate.noThemes')}{' '}
+                    <A href="/themes" class="font-medium underline hover:text-yellow-900">
+                      {t('generate.createThemeLink')}
+                    </A>
+                  </p>
+                </div>
+              }
+            >
+              <div class="mt-4">
+                <label for="theme-select" class="block text-sm font-medium text-gray-700">
+                  {t('generate.selectTheme')}
+                </label>
+                <select
+                  id="theme-select"
+                  value={selectedThemeId()}
+                  onInput={(e) => setSelectedThemeId(e.currentTarget.value)}
+                  class="mt-1 block w-full sm:w-64 rounded-md border-gray-300 shadow-sm focus:border-indigo-500 focus:ring-indigo-500 sm:text-sm"
+                >
+                  <For each={themes()}>
+                    {(theme) => (
+                      <option value={theme.id}>{theme.name}</option>
+                    )}
+                  </For>
+                </select>
+              </div>
+            </Show>
+
             {/* No web search warning */}
             <Show when={settings().ai_provider && !hasWebSearch()}>
               <div class="mt-4 bg-yellow-50 border border-yellow-200 rounded-md p-4">
@@ -382,7 +423,7 @@ const GenerateSynthesis: Component = () => {
                 <button
                   type="button"
                   onClick={handleGenerate}
-                  disabled={generating() || success()}
+                  disabled={generating() || success() || !selectedThemeId()}
                   class="inline-flex items-center justify-center px-4 py-2 border border-transparent font-medium rounded-md text-white bg-indigo-600 hover:bg-indigo-700 focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-indigo-500 sm:text-sm disabled:opacity-50 disabled:cursor-not-allowed w-full sm:w-auto"
                 >
                   <Show when={generating() && !success()}>