diff --git a/tests/test_config.py b/tests/test_config.py
index a942ada..f42e1db 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -76,3 +76,32 @@ class TestConfigPath:
         from whisper_local.config import _default_config_path
         result = _default_config_path()
         assert result == Path.home() / ".config" / "whisper-local" / "config.toml"
+
+
+class TestMicrophoneConfig:
+    def test_default_microphone_is_empty(self):
+        config = Config()
+        assert config.microphone == ""
+
+    def test_load_device_from_toml(self, tmp_path):
+        config_file = tmp_path / "config.toml"
+        config_file.write_text('[audio]\ndevice = "Headset Mic"\n')
+        config = load_config(config_file)
+        assert config.microphone == "Headset Mic"
+
+
+class TestSaveConfig:
+    def test_save_and_reload(self, tmp_path):
+        from whisper_local.config import save_config
+        path = tmp_path / "config.toml"
+        config = Config(hotkey="KEY_F8", microphone="USB Mic")
+        save_config(config, path)
+        loaded = load_config(path)
+        assert loaded.hotkey == "KEY_F8"
+        assert loaded.microphone == "USB Mic"
+
+    def test_save_creates_parent_dirs(self, tmp_path):
+        from whisper_local.config import save_config
+        path = tmp_path / "subdir" / "config.toml"
+        save_config(Config(), path)
+        assert path.exists()
diff --git a/whisper_local/config.py b/whisper_local/config.py
index c2873e9..948e5a5 100644
--- a/whisper_local/config.py
+++ b/whisper_local/config.py
@@ -25,6 +25,7 @@ class Config:
     sample_rate: int = 16000
     channels: int = 1
     min_duration: float = 0.5
+    microphone: str = ""
 
 
 def load_config(path: Path = DEFAULT_CONFIG_PATH) -> Config:
@@ -56,5 +57,23 @@ def load_config(path: Path = DEFAULT_CONFIG_PATH) -> Config:
         config.channels = audio_section["channels"]
     if "min_duration" in audio_section:
         config.min_duration = audio_section["min_duration"]
+    if "device" in audio_section:
+        config.microphone = audio_section["device"]
 
     return config
+
+
+def save_config(config: Config, path: Path = DEFAULT_CONFIG_PATH) -> None:
+    """Schreibt Config als TOML-Datei. Erstellt Verzeichnisse bei Bedarf."""
+    path.parent.mkdir(parents=True, exist_ok=True)
+    content = (
+        f'[hotkey]\nkey = "{config.hotkey}"\n\n'
+        f'[whisper]\nmodel = "{config.whisper_model}"\n'
+        f'language = "{config.language}"\n'
+        f'compute_type = "{config.compute_type}"\n\n'
+        f'[audio]\nsample_rate = {config.sample_rate}\n'
+        f'channels = {config.channels}\n'
+        f'min_duration = {config.min_duration}\n'
+        f'device = "{config.microphone}"\n'
+    )
+    path.write_text(content, encoding="utf-8")