Organisers are trying to find an alternative venue for Mr Galloway, who was suspended from the Labour party over allegations he took money from Saddam Hussein.
He was due to talk at an anti-war meeting in Oxford Town Hall on May 16 at 7pm.
But town hall managers pulled the plug on the event on May 13, after they found out he and two other speakers would be attending.
Liberal Democrat city councillor Fiyaz Mughal had booked the council chamber, which holds about 100 people, on behalf of Oxford Students Stop the War Coalition.
Sue Scarrott, of the town hall bookings department, said: "We would not have accepted this booking if we had been told that these speakers were coming in the first place.
"We thought it was a quiet meeting between the councillor and some students."
Mr Mughal claimed he found out on May 12 that Mr Galloway would be taking part and said he had not realised that so many people had been invited to attend.
OSSWC said Mr Galloway agreed to attend two months ago after he addressed more than 500 anti-war supporters at a meeting in the town hall in February.
Mr Galloway, 49, dubbed a traitor after reportedly urging Arab nations to rise up against British troops during the war against Iraq, was not available for comment.
He is due to talk about British and American involvement in the regeneration of Iraq following the war.
He and author Milan Rai, of the Active Resistance to the Roots of War group, and Ghada Razuki, of Stop the War Coalition, are also expected to question why no weapons of mass destruction had been found in Iraq.
Rick Muir, Labour city councillor for Hinksey ward, said: "Many of us regret that George has been abandoned by our party without any proof of guilt."
But Mick McAndrews, Labour city councillor for Barton and Sandhills, criticised organisers for giving Mr Galloway the chance to have a "public platform on which to spread his anti-British message".
Mr Galloway, who has stood for Labour in Glasgow Kelvin since 1992, has been suspended from his position as MP pending the outcome of a Government inquiry into his dealings with former Iraqi leaders. He denies all accusations.
Comments
Display the following 15 comments