Jean Alexandre Rey was born in Lausanne, Switzerland, in 1861. He obtained French nationality in 1885 and graduated from the Ecole des mines in Paris with a degree in civil engineering in 1886.

In 1888 he becan working for Sautter, Harle and Co., Paris, a company which made lighthouses and signals. He worked there for 35 years, ending up as Managing Director. He also obtained a number of important professional positions, including president of the Professional Federation of Electric Industries and member of the National Economic Council, and a number of learned societies recognised his contribution, for example he was a member of the naval society and was elected to the Academy of Sciences in 1930. Rey was named president of the Society of French civil engineers in 1933.

He published five books and 50 scientific or technical publications, with his work following three main streams:

- Electromechanics: Rey worked on the construction of an internal combustion engine for submarine dynamos

- Optics: Rey was interested in the use of electricity in lighthouses and floodlights, often working with André Blondel, which led to the development of Blondel-Rey Law, which pertains to the relationship between the duration and intensity of flashes of light

- Thermodybamics: Rey invented a new and superior thermo-compressor which transformed the process of evaporating liquids.

Rey also worked on issues surrounding marine warfare, particularly under-water mines operated by battleships. He died in Paris in 1935.