He published articles on the theory of electromagnetic machines which caught the attention of Professor André Blondel at the École des Ponts et Chaussées, who hired Bethenod as an assistant in 1903.

[2] The engineer captain Gustave-Auguste Ferrié (1868–1932) gathered a team to work on wireless telegraphy for the French military.

Bethenod then continued to explore subjects that interested him and wrote many articles in the journal l'Eclairage Electrique (Electric Lighting).

[7] As chief engineer of the SFR Bethenod contributed several inventions in the area of wireless telegraphy including musical spark emitters, high frequency alternators and aircraft radio equipment.

This led to orders for SFR equipment from Belgium, Mexico, Turkey, Bulgaria, Serbia, Italy, Russia and China.

Bethenod was one of the funding vice-presidents of the Société des ingénieurs de l'automobile (Society of Automobile Engineers) in 1927.