Demonstrators will gather at the Brussels North Station starting 11am.
The demonstration starts at noon and will make its way to the South Station where protesters are expected to arrive at 2pm.
The demonstration will be disbanded at 4pm.
The demonstrators will make their way to the South Station via the Willebroekkaai and the central boulevards, Emile Jacqmainlaan, Anspachlaan and Lemonnierlaan.
The liberal union believes as many as 50,000 people could participate.
Brussels police envisage significant disruption.
Police urge the general public not to come to Brussels by car on Thursday.
Parking will be banned along the entire route of the demo.
The Belgian rail company is running eight extra services.
The rail company is marketing a special reduced ticket for people who want to come to Brussels.
The Brussels local transport company MIVB too will be hit by stoppages as workers walk out to take part in the demo, but the socialist union at the MIVB insists that trams, buses and the metro will be operating to a degree on Thursday.
Trades unionist Dario Coppens: “It’s hard to make a forecast, but I’m anticipating that 60 percent of metros, 50 percent of trams and 40 percent of buses will operate.”
Mr Coppens, who speaks on behalf of all the unions at the MIVB, believes people will be able to get to work by public transport.
Like at many companies trades unionists at the MIVB will take part in the demonstration, but places of work will not be picketed.
There will not be any pickets at MIVB bus stations or tram depots and MIVB staff will ensure a service.
Flandersnews.be / Expatica