The project includes the installation of hydrogen fuelling facilities at Clermont-Ferrand.
The trains are due to be delivered in 2022.
French National Railways (SNCF) said last month that it is planning to begin trials with hydrogen trains in 2022 and aims to eliminate diesel traction by 2035.
Auvergne Rhône-Alpes is one of five regions (including Occitanie, Bourgogne Franche-Comté, Grand Est and New Aquitaine) that have agreed to trial hydrogen trains.
Occitanie is planning to carry out trials with three hydrogen Régiolis sets on the 36km Montréjeau - Luchon line in Haute-Garonne, which has been disused since it was damaged by flooding in 2013.
Bourgogne Franche-Comté is also looking to purchase three trains for operation on the Migennes - Auxerre - Morvan line from 2023.
