The pro-democracy Free Youth group asks their supporters to meet first at the Democracy Monument on Wednesday before moving on to the nearby Crown Property Bureau.
In its latest Facebook post, the movement urged people to join them at the monument on Ratchadamnoen Avenue at 3pm.
They will then move to the CPB on Nakhon Ratchasima Road in Bangkok to “reclaim assets that should have belonged to people”.
In 2017, a law was passed to treat public assets as crown assets and have the CPB, a unit under the King, manage them. From 1937, when the system of government was changed to constitutional monarchy, the two types of assets were clearly separated and managed.
Bangkok police said 6,000 policemen would be deployed to handle the protest.
They also warned the demonstrators not to enter the 150m radius of the CPB, where the “royal ground” signpost was put up in front of it earlier this week.
The public assembly law prohibits protests within 150m of palaces or places where royalties reside. Although the CPB is located within the ground of a former palace sold to it in 1945, it is unclear whether the law applies to it.
All roads leading to the CPB will be closed from 4am Wednesday, including the Yommarat ramp on the Expressway.
A new group called Siam Land also announced on Tuesday it would also go the CPB on the same day. It vowed to stop Free Youth protesters from going to the bureau and assured there would be no clashes or violence.