Russian President Dmitry Medvedev invited closer ties with Southeast Asia as he embarks on an Asian tour.
Mr Medvedev will oversee the signing of a multi-billion-euro deal to build Vietnam's first nuclear power plant.
This is one of a number of deals aimed at reviving relations with the Soviet-era Communist ally.
Mr Medvedev's visit started with meetings with the leaders of the ten-member Association of South East Asian Nations in Hanoi, the first Russian-ASEAN summit since the inaugural one in 2005.
Russia has been actively pursuing deals to build nuclear power plants abroad.
It recently completed the reactor at Iran's first nuclear power plant and signed a deal to build a powerful two-reactor station in Venezuela earlier this month.
Russia's Rushydro company and Vietnam's state-owned oil group Petrovietnam would sign an agreement to build a hydroelectric power station, the Kremlin source said.
The power station on the Da river will be upstream from another one already being built by Rushydro.
The source said both countries would also sign a memorandum to help set up the acquisition of British oil group BP's assets in Vietnam by Russian oil firm TNK-BP, which is half owned by BP.
