The Australian author who spent more than five months in a Thai jail for insulting the country's monarchy says he is happy with the way the Australian Government handled his release.

Forty-one-year-old Harry Nicolaides had been jailed for more than three years for insulting a crown prince in a book, but was granted a royal pardon on Thursday night.

He was tearful as he greeted family on his return to Melbourne Airport from Thailand on Saturday afternoon.

Mr Nicolaides says the uncertainty about his future had been gruelling before the pardon was given and he commended the Federal Government's role in his release.

"I was happy with the Australian Government's efforts, they had constraints that they had to work within and the Australian embassy did a marvellous job," he said.

He says he is happy to be home, but angry about his ordeal.

"I am angry, I am frustrated, I am perplexed," he said.

The Federal Government says it did everything it could to lobby for his release.

Foreign Affairs Minister Stephen Smith said he was pleased by the King's decision.

"We believe that we did everything that we could," he told reporters in Perth.

"I welcome the fact that so soon after his pardon he has returned to his family and Australia."

"I think it is a measure of the good relationship between Australia and Thailand that the pardon was granted by the King of Thailand on Wednesday, the paperwork was completed on Friday and less than a day later, with the assistance of the Thai authorities, he was returned to Australia."

Opposition foreign affairs spokeswoman Julie Bishop also welcomed Mr Nicolaides' return.

"The imprisonment of Mr Nicolaides has been a traumatic experience for him and his family, particularly his elderly parents," she said in a statement.

"We are relieved that the appeals for clemency have been given sympathetic consideration by the king."

Mr Nicolaides says he plans to write a tell-all book.

- ABC/AAP