A communications satellite for Intelsat was shot into orbit from an oceangoing rocket platform in the equatorial Pacific.
An Associated Press report quoted operator Sea Launch as saying that the Galaxy 18 satellite will provide TV, data and telecoms services.
A Zenit-3SL rocket carrying the 10,234-pound satellite lifted off from the Odyssey launch platform, said Paula Korn, spokeswoman for Long Beach, California-based Sea Launch.
All systems performed normally and the satellite's first signals were received at a ground station in South Africa, the company said. Galaxy 18 was built by Space Systems/Loral.
Sea Launch is owned by Boeing, RSC-Energia of Russia, Aker ASA of Norway and SDO Yuzhnoye/PO Yuzhmash of Ukraine.