Two French security advisors on a mission to train Somali forces were kidnapped at a hotel where they had checked in as journalists, officials and witnesses said.
The French Foreign Ministry released a statement saying the men were security consultants.
No claim of responsibility or demand for a ransom was reported from the kidnappers.
Foreigners rarely go to Mogadishu, the Somali capital, which is among the most dangerous cities in the world, and when they do, they travel only in convoys with armed guards. Kidnappings for ransom have been on the rise in recent years, with journalists and aid workers often targeted.