"He will be making his announcement later today," the source said.
Bubka will join Germany's Thomas Bach, Singapore's Ng Ser Miang, C.K. Wu of Taiwan, Puerto Rican Richard Carrion and Swiss Denis Oswald in a six-way race for one of the biggest jobs in world sport.
The Ukrainian six-times world champion, who won gold at the Seoul 1988 Olympics, is a member of the powerful IOC Executive board as well as a world athletics senior vice president.
Before deciding to run for the top Olympic job, Bubka, still the world record holder in his sport, was seen as one of two likely candidates to succeed Lamine Diack as head of the IAAF, with the other being London 2012 Games chief Sebastian Coe.
The IOC will elect the successor to Belgian surgeon Jacques Rogge, who 12-year stint at the helm comes to a mandatory end, at their session in Buenos Aires on September 10.
All but one of the IOC presidents in the history of the organisation have been Europeans.
- Sports & Recreation
- Ng Ser Miang