Mr Hooper is supposed to be sworn-in at council meeting on Wednesday following Margaret Strelow's resignation over misconduct involving Indian mining firm Adani, now known as Bravus in Australia.

He received about 30 per cent of the vote in March election, but as runner-up he's legally entitled to be mayor.

Rockhampton Council has postponed Wednesday's meeting and will instead be briefed on proposed retrospective state laws, which will force a by-election in the city.

The Queensland government will table the new laws in parliament on Thursday, effectively preventing Mr Hooper from becoming mayor.

He has written to the council, the state government and the electoral commission to warn that failing to appoint him in the role is illegal.

"I urge you to change that outrageous decision and to hold the Council meeting tomorrow as scheduled and comply with the law and appoint me as Mayor tomorrow," Mr Hooper wrote in a letter posted on Facebook on Tuesday.

"It is unacceptable that you are breaching the law."

The activist called on the council to reschedule the meeting and confirm his swearing-in appointment.

Mr Hooper threatened legal action against the chief executive officer Evan Pardon, acting mayor Neil Fisher and the councillors.

"If the appointment is not made, be advised I reserve my rights to pursue urgent legal action against each of you, including claiming costs, in the Supreme Court to compel compliance with the Local Government Act 2009," he wrote.

"Yours sincerely, Mr Chris Hooper, Mayor Elect."

Mr Fisher said earlier the briefing was essential as the proposed laws could invalidate any decisions made by Mr Hooper.

He said the laws would affect any critical documentation he signed and the day-to-day duties of the mayor.

"Council has a responsibility to the community to ensure we are fully informed and understand the nature of the implications as a result of the proposed legislative amendments. This is simply good governance," Mr Fisher told AAP in a statement.

Deputy Premier and Local Government Minister Steven Miles said last week the proposed laws are likely to be the first legislation introduced to the new parliament.

He denied the government was targeting Mr Hooper, saying Labor took the laws to last month's state election.

"He's very, very welcome to nominate in that by-election, and if he is chosen by the people of Rockhampton to be their mayor then that's entirely appropriate," Mr Miles said.

The Council Conduct Tribunal found Ms Strelow guilty of misconduct earlier this month, ruling she had failed to declare a $1600 trip to an Adani solar plant in Mumbai in 2017.

Ms Strelow and Townsville Mayor Jenny Hill later announced their councils would fund a $30 million airport for the company's Carmichael coalmine in central Queensland.

Australian Associated Press