The 19th-century neo-classical artist Jean Leon Gerome's 'Piscine du Harem' ('Harem Pool') was handed over to Hermitage officials at an international UNESCO World Heritage conference, which opened at the museum earlier in the day.
The canvas, which went missing in March 2001, resurfaced late last year when a man called a Communist Party office in Moscow saying he would like to offer it as a gift to the party's boss, Gennady Zyuganov. The politician said the painting had been sliced up, and was in terrible condition.
The head of the government's cultural heritage protection agency, Boris Boyarskov, said at Monday's handover ceremony that the painting would need major restoration.
One of the world's richest and finest art collections, the Hermitage has recently found itself at the center of several high-profile theft scandals, raising concerns over security in the country's museums.
Last year, President Vladimir Putin ordered a nationwide audit of major state collections after a routine inventory check at the Hermitage uncovered that more than 220 items, worth an estimated $5 million, were missing from the museum's Russian medieval art section.
An investigation found that a Hermitage custodian entrusted with safeguarding the unit's holdings was involved in the mass theft, and that her husband and son had acted as accomplices. The museum employee died of a heart attack shortly after the inspection began.
