Decauville (French: [dəkovil]) was a manufacturing company which was founded by Paul Decauville (1846–1922), a French pioneer in industrial railways. Decauville's major innovation was the use of ready-made sections of light, narrow-gauge track fastened to steel sleepers; this track was portable and could be disassembled and transported very easily.
The first Decauville railway used 400 mm (15+3⁄4 in) gauge; Decauville later refined his invention and switched to 500 mm (19+3⁄4 in) and 600 mm (1 ft 11+5⁄8 in) gauge.