The first trains on the Sukhumvit line will leave from Mo Chit and Bearing stations at 5.15am and the Silom line will start its service at 5.30am from the National Stadium and Bang Wa stations for the Silom line from March to August, Bangkok Mass Transit System Plc chief operating officer Surapong Laoha-Unya said on Thursday.
But train staff will not be providing counter services or topping up travel cards and exchanging coins before 6am and after 11.45pm, he said.
The firm operates the BTS system.
The skytrain currently operates from 6am to midnight.
Passengers can check the service timetable to see what times the trains will reach the other stations.
Mr Surapong said the adjustment came into consideration after many commuters sent in requests for the skytrain to open before 6am.
The company will conduct an evaluation after the six-month period and later decide on whether to make the changes permanent, he said.