diff --git a/frontend/src/components/ExportDataModal.jsx b/frontend/src/components/ExportDataModal.jsx
new file mode 100644
index 0000000..3e0e2c1
--- /dev/null
+++ b/frontend/src/components/ExportDataModal.jsx
@@ -0,0 +1,108 @@
+import React, { useEffect, useMemo, useState } from 'react';
+import { experimentsApi } from '../api/client';
+import Button from './ui/Button';
+import Alert from './ui/Alert';
+import { listExportableParams, buildMatrix, toCSV, csvFilename } from '../lib/dataExport';
+
+const GROUP_LABELS = { metrics: 'Session metrics', daily: 'Daily record fields' };
+
+function triggerDownload(filename, text) {
+  const blob = new Blob([text], { type: 'text/csv;charset=utf-8;' });
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = url;
+  a.download = filename;
+  document.body.appendChild(a);
+  a.click();
+  document.body.removeChild(a);
+  URL.revokeObjectURL(url);
+}
+
+export default function ExportDataModal({ experimentTitle, experimentId, dailyTemplate, animals, onClose }) {
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState(null);
+  const [statuses, setStatuses] = useState([]);
+  const [selectedId, setSelectedId] = useState(null);
+
+  useEffect(() => {
+    let alive = true;
+    setLoading(true);
+    setError(null);
+    experimentsApi.getDailyStatuses(experimentId, {})
+      .then((data) => { if (alive) setStatuses(data); })
+      .catch((err) => { if (alive) setError(err.message); })
+      .finally(() => { if (alive) setLoading(false); });
+    return () => { alive = false; };
+  }, [experimentId]);
+
+  const params = useMemo(() => listExportableParams(dailyTemplate, statuses), [dailyTemplate, statuses]);
+
+  // Default the selection to the first parameter once params are available.
+  useEffect(() => {
+    if (selectedId === null && params.length > 0) setSelectedId(params[0].id);
+  }, [params, selectedId]);
+
+  const selectedParam = params.find((p) => p.id === selectedId) ?? null;
+
+  const matrix = useMemo(
+    () => (selectedParam ? buildMatrix(statuses, animals, selectedParam) : { columns: [], rows: [] }),
+    [statuses, animals, selectedParam],
+  );
+
+  const hasData = matrix.rows.length > 0;
+
+  // Group params for <optgroup> rendering, preserving order.
+  const grouped = useMemo(() => {
+    const out = [];
+    for (const p of params) {
+      let g = out.find((x) => x.group === p.group);
+      if (!g) { g = { group: p.group, items: [] }; out.push(g); }
+      g.items.push(p);
+    }
+    return out;
+  }, [params]);
+
+  function handleExport() {
+    if (!hasData || !selectedParam) return;
+    triggerDownload(csvFilename(experimentTitle, selectedParam.label), toCSV(matrix));
+    onClose();
+  }
+
+  if (loading) return <p className="text-sm text-gray-400" aria-live="polite">Loading data…</p>;
+  if (error) return <Alert type="error" message={error} />;
+
+  return (
+    <div className="space-y-4">
+      <p className="text-sm text-gray-500">
+        Export one parameter as a CSV file — each row is a date, each column is a subject.
+      </p>
+
+      <div>
+        <label htmlFor="export-param" className="block text-xs font-medium text-gray-500 mb-1">Parameter</label>
+        <select
+          id="export-param"
+          value={selectedId ?? ''}
+          onChange={(e) => setSelectedId(e.target.value)}
+          className="w-full border border-gray-200 rounded px-2 py-1.5 text-sm bg-white focus:outline-none focus:ring-1 focus:ring-indigo-400"
+        >
+          {grouped.map((g) => (
+            <optgroup key={g.group} label={GROUP_LABELS[g.group] ?? g.group}>
+              {g.items.map((p) => <option key={p.id} value={p.id}>{p.label}</option>)}
+            </optgroup>
+          ))}
+        </select>
+      </div>
+
+      <p className="text-xs text-gray-400">
+        {hasData
+          ? `${matrix.rows.length} date${matrix.rows.length !== 1 ? 's' : ''} × ${matrix.columns.length} subject${matrix.columns.length !== 1 ? 's' : ''}`
+          : 'No data for this parameter yet.'}
+      </p>
+
+      <div className="flex justify-end gap-2 pt-2">
+        <Button variant="secondary" onClick={onClose}>Cancel</Button>
+        <Button onClick={handleExport} disabled={!hasData}>Export CSV</Button>
+      </div>
+    </div>
+  );
+}