Hilaire Bernigaud, count de Chardonnet (born May 1, 1839, Besançon, France—died March 12, 1924, Paris) was a French chemist and industrialist who first developed and manufactured rayon.

Trained as a civil engineer after completing scientific studies under Louis Pasteur, Chardonnet began to develop an artificial fibre in 1878. Obtaining a patent in 1884 on a fibre produced by extruding a solution of cellulose nitrate through fine glass capillaries, he worked for several years on the problem of reducing the flammability of the new substance. At the Paris Exposition of 1889 he showed rayon products to the public for the first time. Soon afterward he opened a factory, Société de la Soie de Chardonnet (“Society of the Silk of Chardonnet”) in Besançon, which in 1891 began to produce the world’s first commercially made synthetic fibre, sometimes called Chardonnet silk to distinguish it from other forms of rayon.