The project - from Harry's Law creator David E Kelley - is based on CNN medical correspondent Dr Sanjay Gupta's novel Monday Mornings.
It will chart the careers and personal lives of five surgeons working in a high-pressure environment.
Molina will play Dr Harding Hooten, the ruthless Chief of Surgery, according to Deadline.
Best known for his roles in such films as 1981's Raiders of the Lost Ark and 2004's Spider-Man 2, Molina's past television credits include short-lived NBC crime spinoff Law & Order: Los Angeles and a recurring role on Harry's Law.
Bill Irwin - who recently played serial killer Nate Haskell on CSI - will appear alongside Molina as Buck Tierney, a smug doctor who is disliked by his colleagues.
Kelly and Gupta will executive produce Chelsea General, with Boston Legal's Bill D'Elia hired to direct the pilot.
Other projects in the works at TNT include Frank Darabont's L.A. Noir and police dog drama Scent of the Missing starring Tricia Helfer.
> Jamie Bamber joins David E Kelley's medical drama Chelsea General