The 20 cent coin, featuring Mothball the wombat chomping on a carrot, has been released to celebrate the 20^th anniversary of Diary of a Wombat, which French wrote after watching a rambunctious wombat making mischief in her garden.

The much-loved book went on to become an international bestseller. Now it has been commemorated with the release of the uncirculated coin - meaning the coin is available to buy from the Mint by collectors but won't see it turning up in your change at the shops any time soon.

Ms French, who lives at Araluen, reunited with Mr Whatley, who lives at Jervis Bay, for the coin launch at the Mint in Deakin. She said having their creation on a coin was "seriously cool".

"I cannot tell you the amount of joy these books have given us. And to actually see that there is a coin with the very serious Queen on one side and this incredibly mischievous wombat grin on the other just seems somehow incredibly, totally Australian," she said.

"And to have a coin with joy in it is wonderful."

The Mint's product development officer Matthew Frawley said 40,000 Diary of a Wombat coins had been produced and 3000 gold-plated ones also released for serious collectors.

"For many years, the Mint has commemorated classic Australian children's literature on coins. These coins resonate with generations of Australians and will be treasured for years to come," Mr Frawley said.

"There is a strong emotional connection between people and books, especially if they read them as children and then grow up to read them to the following generations. Putting beloved book characters on coins, is a wonderful way to bring Australia's numismatic and bibliophilic community together."

Ms French and Mr Whatley gave a special reading of the book to local children and revealed some insights into how Mothball the wombat came to be created in literary form.

"Diary of a Wombat, it was the funniest thing I'd ever read, okay?," Mr Whatley said.

"And I was fortunate in that, this doesn't happen very often, but I saw the character immediately and the character was actually based on an English bulldog I had at the time. It was the same attitude, the same stubbornness."

He was thrilled to see that wombat now being honoured in such a special way.

"Who would have thought 20 years ago that a humble wombat who basically just ate, scratched and slept would find itself immortalised on an Australian coin? I'm sure Mothball, being so humbly proud and immensely grateful of this recognition, will keep one in her pouch at all times," he said.

The Diary of a Wombat coin was developed with the Children's Book Council of Australia ahead of its Book Week from August 20-26, helping to promote reading in schools and libraries across the nation.