Officially called the Mass Rapid Transit (MRT) and in Thai as rot fai fah mahanakhon ("metropolitan electric train") or more often as the rot fai tai din ("underground train") the line operates from 5am to midnight, and extends in a wide loop from the main railway station of Hualumpong, then tracks back via the Queen Sirikit National Convention Centre to the smaller rail station of Bang Sue to the north.

It has interchanges with the Skytrain at Si Lom, Sukhumvit and Chatuchak Park stations. To protect against periodic flooding, station entrances are elevated above ground, and equipped with built-in floodgates. To prevent accidents and suicides, a glassed-in Automatic Platform Screen Door separates the platform and track, and opens only when the trains pull in and stop. All stations feature lifts and ramps for disabled people.

As with the Skytrain, there are a number of ticket types, which only need to be held close to the ticket barriers to operate them, thanks to a proximity sensor. Tokens are used for single journeys. An unlimited 1 day go-as-you please travel ticket currently costs Baht 120.