The St.Petersburg City Court found Yevgeny Afanasyev and Svyatoslav Bobyshev guilty of treason and sentenced them to 12 1/2 and 12 years in prison respectively, according to the Interfax news agency.
The two professors of St.Petersburg's Baltic State Technological University were accused of selling confidential information related to Russia's latest intercontinental ballistic missile, the Bulava, to representatives of China's military intelligence. The two men have been in custody since their arrest in March 2010.
After decades of Cold War-era rivalry, Moscow and Beijing have developed what they call a strategic partnership after the 1991 Soviet collapse. China also has become a major customer for Russian weapons industries, although Russian arms exports have drained in recent years as China has sought to produce unlicensed copycat versions of Russian weapons.
Russia also has refrained from providing China with some of the latest military technologies, and a number of Russian scientists have been convicted of spying for China in recent years.
The Bulava, designed to equip a new generation of Russian nuclear submarines, suffered a string of failures during its development phase but recent test launches went successfully.
Interfax said that the professors were accused of providing the Chinese with technological details related to the Bulava's underwater launch during their trip to China in 2009. It said that Chinese intelligence also sought information about the land-based Topol-M and Iskander missiles.