diff --git a/package-lock.json b/package-lock.json
index 4a52c2a..f9e5acb 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -23,6 +23,8 @@
         "@tiptap/extension-paragraph": "^3.23.6",
         "@tiptap/extension-placeholder": "^3.23.6",
         "@tiptap/extension-strike": "^3.23.6",
+        "@tiptap/extension-subscript": "^3.23.6",
+        "@tiptap/extension-superscript": "^3.23.6",
         "@tiptap/extension-table": "3.23.6",
         "@tiptap/extension-text": "^3.23.6",
         "@tiptap/extension-text-align": "^3.23.6",
@@ -643,6 +645,34 @@
         "@tiptap/core": "3.23.6"
       }
     },
+    "node_modules/@tiptap/extension-subscript": {
+      "version": "3.23.6",
+      "resolved": "https://registry.npmjs.org/@tiptap/extension-subscript/-/extension-subscript-3.23.6.tgz",
+      "integrity": "sha512-K9NP2sAjoQ0EKnPVw96864aMXZlK5r3cTaybg7vQ6kKIM9OEOB+36F4VHQgQdpYUMk94gxSP/ixBB8bTVN8lPA==",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/ueberdosis"
+      },
+      "peerDependencies": {
+        "@tiptap/core": "3.23.6",
+        "@tiptap/pm": "3.23.6"
+      }
+    },
+    "node_modules/@tiptap/extension-superscript": {
+      "version": "3.23.6",
+      "resolved": "https://registry.npmjs.org/@tiptap/extension-superscript/-/extension-superscript-3.23.6.tgz",
+      "integrity": "sha512-GTVHfik32a6m4q8rU3nl0mUKUfz3kTd+qIxUCGvoS/1Adb9M5Q0i5bfLk5jDOW896iCn00hPW7GbkP7WRd2Mhg==",
+      "license": "MIT",
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/ueberdosis"
+      },
+      "peerDependencies": {
+        "@tiptap/core": "3.23.6",
+        "@tiptap/pm": "3.23.6"
+      }
+    },
     "node_modules/@tiptap/extension-table": {
       "version": "3.23.6",
       "resolved": "https://registry.npmjs.org/@tiptap/extension-table/-/extension-table-3.23.6.tgz",
diff --git a/package.json b/package.json
index d1af54c..36062dc 100644
--- a/package.json
+++ b/package.json
@@ -37,6 +37,8 @@
     "@tiptap/extension-paragraph": "^3.23.6",
     "@tiptap/extension-placeholder": "^3.23.6",
     "@tiptap/extension-strike": "^3.23.6",
+    "@tiptap/extension-subscript": "^3.23.6",
+    "@tiptap/extension-superscript": "^3.23.6",
     "@tiptap/extension-table": "3.23.6",
     "@tiptap/extension-text": "^3.23.6",
     "@tiptap/extension-text-align": "^3.23.6",
diff --git a/src/lib/editor/ToolbarExpanded.svelte b/src/lib/editor/ToolbarExpanded.svelte
index 9fa3afb..6e41229 100644
--- a/src/lib/editor/ToolbarExpanded.svelte
+++ b/src/lib/editor/ToolbarExpanded.svelte
@@ -270,6 +270,19 @@
   let currentFontColor = $derived(uniformMarkColor('textStyle'));
   let currentHighlightColor = $derived(uniformMarkColor('highlight'));
 
+  // Sub/superscript are mutually exclusive (Word-style): toggling one clears the
+  // other. odf-kit maps these marks to text:position (round-trips with LibreOffice
+  // and Word). See export/odt.ts applyRuns for the custom-attr-paragraph path.
+  let isSuperscript = $derived(tick >= 0 && !!editor?.isActive('superscript'));
+  let isSubscript = $derived(tick >= 0 && !!editor?.isActive('subscript'));
+
+  function toggleSuperscript() {
+    editor?.chain().focus().unsetSubscript().toggleSuperscript().run();
+  }
+  function toggleSubscript() {
+    editor?.chain().focus().unsetSuperscript().toggleSubscript().run();
+  }
+
   let fontOpen = $state(false);
   let sizeOpen = $state(false);
   let lineHeightOpen = $state(false);
@@ -777,6 +790,33 @@
 
     <div class="toolbar-separator"></div>
 
+    <div class="toolbar-group">
+      <button
+        class:active={isSuperscript}
+        onclick={toggleSuperscript}
+        title="Superscript (Ctrl+.)"
+        aria-pressed={isSuperscript}
+      >
+        <svg width="16" height="16" viewBox="0 0 16 16" fill="none" aria-hidden="true">
+          <path d="M2.5 11.5L7 5M7 11.5L2.5 5" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/>
+          <path d="M10.5 4.7c0-.8.7-1.4 1.5-1.4s1.5.6 1.5 1.4c0 1.2-1.6 1.5-3 3.1h3" stroke="currentColor" stroke-width="1.2" stroke-linecap="round" stroke-linejoin="round"/>
+        </svg>
+      </button>
+      <button
+        class:active={isSubscript}
+        onclick={toggleSubscript}
+        title="Subscript (Ctrl+,)"
+        aria-pressed={isSubscript}
+      >
+        <svg width="16" height="16" viewBox="0 0 16 16" fill="none" aria-hidden="true">
+          <path d="M2.5 11.5L7 5M7 11.5L2.5 5" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/>
+          <path d="M10.5 12.2c0-.8.7-1.4 1.5-1.4s1.5.6 1.5 1.4c0 1.2-1.6 1.5-3 3.1h3" stroke="currentColor" stroke-width="1.2" stroke-linecap="round" stroke-linejoin="round"/>
+        </svg>
+      </button>
+    </div>
+
+    <div class="toolbar-separator"></div>
+
     <div class="lh-picker" use:lineHeightPickerClickOutside>
       <button class="lh-trigger" onclick={openLineHeightPicker} title="Line &amp; paragraph spacing">
         <svg width="16" height="16" viewBox="0 0 16 16" fill="none" aria-hidden="true">
diff --git a/src/lib/editor/extensions.ts b/src/lib/editor/extensions.ts
index 54181c7..d25bda9 100644
--- a/src/lib/editor/extensions.ts
+++ b/src/lib/editor/extensions.ts
@@ -5,6 +5,8 @@ import Bold from '@tiptap/extension-bold';
 import Italic from '@tiptap/extension-italic';
 import Underline from '@tiptap/extension-underline';
 import Strike from '@tiptap/extension-strike';
+import Subscript from '@tiptap/extension-subscript';
+import Superscript from '@tiptap/extension-superscript';
 import Highlight from '@tiptap/extension-highlight';
 import { TextStyle, FontFamily, FontSize } from '@tiptap/extension-text-style';
 import { FontWeight } from './fontWeight';
@@ -34,6 +36,8 @@ export const extensions = [
   Italic,
   Underline,
   Strike,
+  Subscript,
+  Superscript,
   TextStyle,
   FontFamily,
   FontSize,
diff --git a/src/lib/export/odt.ts b/src/lib/export/odt.ts
index ae16e61..1c02f5b 100644
--- a/src/lib/export/odt.ts
+++ b/src/lib/export/odt.ts
@@ -552,6 +552,8 @@ function applyRuns(p: ParagraphBuilder | CellBuilder, content: TiptapNode[] = []
     if (marks.some(m => m.type === 'italic'))     fmt.italic = true;
     if (marks.some(m => m.type === 'underline'))  fmt.underline = true;
     if (marks.some(m => m.type === 'strike'))     fmt.strikethrough = true;
+    if (marks.some(m => m.type === 'superscript')) fmt.superscript = true;
+    else if (marks.some(m => m.type === 'subscript')) fmt.subscript = true;
     if (tsm?.attrs?.fontFamily) {
       const ff = String(tsm.attrs.fontFamily);
       // Explicitly choosing the editor default should match the untagged