EXCLUSIVE: Peter O'Sullivan is preparing a legal challenge against his former employer Gladstone Ports Corporation after he was accused of misconduct and sacked as chief executive officer.

The former Ports boss of three years was suspended with pay in December last year while an investigation was conducted into a complaint about how he handled a staff disciplinary matter.

On Monday night, GPC confirmed Mr O'Sullivan had been dismissed after a "thorough and extensive" investigation.

Mr O'Sullivan refutes the allegations and claims the corporation's board was trying to "push him out".

Speaking exclusively to The Observer he said the past five months had been "extremely difficult" for him, his wife and two children.

"It's been extremely distressing for the entire family," he said.

"I was the principal of the high school before this and I pride myself that I've always held myself on high ethical standards.

"You don't sleep, it's very difficult to maintain your friendship circles too.

"You go out and people ask 'what's going on' and you can't talk about it."

In December 2018, Mr O'Sullivan was made aware of 12 allegations made towards him.

He said after he replied to the allegations 10 were dropped, with the two remaining relating to an investigation which he ordered into a workplace complaint.

He said the board alleged he had ordered the investigation for an "improper purpose" and he was "vague and inconsistent" during the investigation.

Issues with the board's investigation and decision have been referred to the Crime and Corruption Commission by Mr O'Sullivan.

He has also sought legal advice on how to challenge the allegations.

"It's extremely disappointing for myself and my family for (the board) to do this and to have your name splashed on the front page of the paper when you firmly believe that you haven't done anything that relates to misconduct that requires a dismissal," he said.

Mr O'Sullivan claims some members of the board should not have been involved in the decision-making process, because they were among those who made the allegations.

"I've never been part of an organisation which would allow someone who's made an allegation to be part of the procedural process," he said.

"I'm not someone to stand idly by when an unfair and unreasonable process is being done.

"It gives me grave concerns in how GPC is being managed."

Mr O'Sullivan said his concerns about the board of the Queensland Government-owned corporation began in August last year.

"To see the port on the front page of the Courier Mail and The Australian for all the wrong reasons, it's extremely disappointing and the shareholding ministers need to step in and take some action," he said.

"What's disappointing for me is it destroys the reputation of the port."

In August last year, former chairman Leo Zussino was stood aside.

At the time a complaint had been made to the Crime and Corruption Commission regarding the way the business was run.

The complaint was referred to Queensland Treasury in October last year and today the department told The Observer its investigation was ongoing.

Queensland Ports Minister Mark Bailey said the government made it clear GPC's focus should be "squarely on growing trade, supporting local jobs and our regional economy".

He said Mr O'Sullivan's dismissal was the result of a thorough investigation.

Chairman Peter Corones said in a statement to The Observer last night the board's decision was a result of its own investigation.

Mr Corones defended the port's senior management team and said it would be "business as usual" for customers, stakeholders and the community until a new CEO was appointed.

He did not respond to questions about if the allegations were part of a bid by the board to "push out" Mr O'Sullivan.

He said GPC would immediately start a merit-based search for its new leader.

Craig Walker, who has been acting chief executive officer since late last year, will continue in the role until a permanent replacement is found.