diff --git a/pkgs/by-name/th/themix-gui/package.nix b/pkgs/by-name/th/themix-gui/package.nix
new file mode 100644
index 000000000000..c73724a0ca27
--- /dev/null
+++ b/pkgs/by-name/th/themix-gui/package.nix
@@ -0,0 +1,78 @@
+{ lib
+, stdenv
+, sassc
+, gdk-pixbuf
+, glib
+, gobject-introspection
+, librsvg
+, gtk3
+, python3
+, fetchFromGitHub
+, wrapGAppsHook
+}:
+
+let
+  py = python3.withPackages (p: [
+    p.pygobject3
+  ]);
+  pname = "themix-gui";
+  version = "1.15.1";
+in
+stdenv.mkDerivation {
+  inherit pname version;
+
+  src = fetchFromGitHub {
+    owner = "themix-project";
+    repo = "themix-gui";
+    rev = version;
+    hash = "sha256-xFtwNx1c7Atb+9yorZhs/uVkkoxbZiELJ0SZ88L7KMs=";
+    fetchSubmodules = true;
+  };
+
+  nativeBuildInputs = [
+    gobject-introspection
+    py
+    sassc
+    wrapGAppsHook
+  ];
+
+  buildInputs = [
+    gdk-pixbuf
+    glib
+    gtk3
+    librsvg
+    py
+  ];
+
+  postPatch = ''
+    substituteInPlace gui.sh packaging/bin/{oomox,themix}-gui --replace python3 ${lib.getExe py}
+  '';
+
+  dontBuild = true;
+
+  installPhase = ''
+    runHook preInstall
+
+    make DESTDIR=/ APPDIR=$out/opt/oomox PREFIX=$out install_gui install_import_xresources install_export_xresources
+    python -O -m compileall $out/opt/oomox/oomox_gui -d /opt/oomox/oomox_gui
+
+    runHook postInstall
+  '';
+
+  meta = {
+    description = "Graphical application for designing themes and exporting them using plugins";
+    longDescription = ''
+      Graphical application for generating different color variations of
+      Oomox (Numix-based) and Materia (ex-Flat-Plat) themes (GTK2, GTK3,
+      Cinnamon, GNOME, Openbox, Xfwm), Archdroid, Gnome-Color, Numix, Papirus
+      and Suru++ icon themes. Have a hack for HiDPI in gtk2. Its Base16 plugin
+      also allowing a lot of app themes support like Alacritty, Emacs, GTK4,
+      KDE, VIM and many more.
+    '';
+    homepage = "https://github.com/themix-project/themix-gui";
+    license = lib.licenses.gpl3Only;
+    mainProgram = "themix-gui";
+    maintainers = with lib.maintainers; [ eclairevoyant ];
+    platforms = lib.platforms.linux;
+  };
+}