The agreement is about the construction and delivery of emergency engines called Adria 40, which will pave the way for similar projects in the future.
The 10-million-euro agreement is Adriadiesel's biggest deal in the past 15 years.
The project is being financed by the Russian government agency Rosenergoatom.
Adriadiesel, established in 1949, manufactures diesel engines and spare parts, as well as other power equipment, and it also provides overhaul, machining and heat treatment services.