Calpine's chief executive officer Robert May is to leave the company, which emerged from a two-year bankruptcy process in January, once a successor is in place.

"Now Calpine has emerged as a strong, focused competitor with an appropriate financial structure, the time is right to identify a successor who will take Calpine to the next level," says May.

The Calpine board has formed a search committee and will be selecting an executive search firm to identify qualified candidates to lead the company