A native of Oyonnax in the Ain region, Gustave Mermet-Guyenet is a comb manufacturer.

As part of his professional activities, he was a member of the board of the chamber of comb manufacturers from 1901 to 1914. He also chaired the Conseil de perfectionnement de l'école nationale des matières plastiques and was a technical education advisor.

Wounded in the First World War, during which he served as a sergeant rifleman, Gustave Mermet-Guyenet began his political career at local level after the conflict.

He was elected to the Oyonnax town council in 1919, a position he held until 1939. From 1920 to 1939, he was deputy mayor. He founded and chaired the Oyonnax municipal harmony, as well as various local societies. In 1920, he joined the French Communist Party, later becoming president of the Association des élus communistes de l'Ain. Already full of precocious political convictions, Gustave Mermet-Guyenet founded the Jeunesse Socialiste group in 1899 at the age of 14.

During the Second World War, Gustave Mermet-Guyenet was expelled from the army and interned in 1942-1943 at Saint Paul d'Eygeaux (Haute-Vienne). On December 14, 1943, during the "Oyonnax massacres", he narrowly escaped being shot by the Gestapo. He was reinstated as mayor by the Resistance in July 1945. He was then chosen to be mayor of his liberated town until the first municipal elections. He represented the Communist Party on the departmental Liberation Committee.

In 1946, the PCF asked Gustave Mermet-Guyenet to stand as a candidate for the first elections to the Council of the Republic. At the Palais du Luxembourg, Gustave Mermet-Guyenet, who had joined the Communist group, was appointed a member of the economic affairs, customs and trade agreements commission, as well as the pensions and supplies commissions. His speeches concerned a rebate for war victims and a special levy to combat inflation. In 1948, on the subject of public works, Gustave Mermet-Guyenet highlighted the slow pace of reconstruction work on the Bourg-en-Bresse to Bellegarde viaduct. He also commented on the number of technical teaching staff and the legal status of industrial technical centers.

In the elections held on November 7, 1948, he was defeated when he stood for election on the Republican and Resistance Union list, which failed to win any seats. He was also unsuccessful in the by-election of October 21, 1951, triggered by the election of Jean Saint-Cyr, a radical senator, to the National Assembly, and in the election of June 19, 1955, when he ran on the list of workers' and peasants' defense and democratic union presented by the Communist Party.

GUSTAVE MERMET-GUYENNET , Republic Councillor for the Ain department. His election is validated [(S. December 27, 1946] (p. 29).

He is appointed member of :

• the Committee on Economic Affairs, Customs and Trade Agreements [January 28, 1947] (p. 14)
• Commission des pensions (pensions civiles et militaires et victimes de la guerre et de l'oppression) [May 20, 1947] (p. 575).