The Salmson water-cooled aero-engines, produced in France by Société des Moteurs Salmson from 1908 until 1920,[1] were a series of pioneering aero-engines: unusually combining water-cooling with the radial arrangement of their cylinders.

Henri Salmson, a manufacturer of water pumps, was engaged by Georges Marius Henri-Georges Canton and Pierre Unné, a pair of Swiss engineers, to produce engines to their design.

Their initial efforts were on barrel engines, but these failed to meet expectations due to low reliability and high fuel consumption caused by internal friction.

By 1912 the Salmson A9 was producing around 120 brake horsepower; while competitive with rival designs from French companies, Salmson, Canton and Unné decided to develop more powerful engines as their rivals were concentrating on engines of lower power.

The Salmson-(Canton-Unne) series of water-cooled engines were also built by licensees in Russia and in Great Britain at the Dudbridge Iron Works Limited at Stroud in Gloucestershire between 1914 and 1918.