An electronic keyboard instrument, invented in 1941 by the Frenchman Georges Jenny, and a forerunner of today's synthesisers.

The Ondioline was capable of creating a wide variety of sounds. Its keyboard had a unique feature: it was suspended on special springs which made it possible to introduce a natural vibrato if the player moved the keyboard from side to side with their playing hand. The keyboard was also pressure-sensitive and the instrument had a knee volume lever.

The instrument's movable keyboard was modelled after that of another early electronic instrument from France, the Ondes Martenot. The Ondioline did not feature a ring (or ribbon) controller to control pitch, as did the Ondes, but instead had a strip of wire that when pressed provided percussion effects. But it could not produce the Ondes's theremin-like pitch effects.

However, the Ondioline's sounds possibilities were much more varied. This was due to its filter bank, which featured an array of 15 slider switches for various tones. Selected combinations of these switches could create sounds ranging from near-accurate recreations of symphonic instruments (oboe, French horn, etc.) to totally unique sounds of its own.