The Blue Line began charging fares to passengers on its extended route from Hua Lamphong to Lak Song station on Sunday, ending free rides offered during the trial run.
The MRT line extension, which officially launched on Sunday has started charging passengers 16-42 baht for a ride to its 11 new stations until the terminus at Lak Song.
Bangkok residents were able to try the service from Hua Lamphong to Tha Phra stations free of charge after its operator started a two-month trial run on July 29.
Bangkok Expressway and Metro Plc (BEM), the company that operates the Blue Line, offered a 16-kilometre-long free ride from Hua Lamphong to Lak Song from July 28 until Saturday.
Government spokeswoman Narumon Pinyosinwat said on Sunday Prime Minister Prayut Chan-o-cha will ride the new rail extension from Tha Phra to Wat Mangkon on Monday. A BEM official said the prime minister's ride will start at 9am.
The MRT plans to open another new route from Tao Poon to Tha Phra in the first quarter of next year to complete the loop.