Allan Stewart became the world’s oldest graduate when he earned a law degree aged 91.

He will surpass his own record on Friday when he graduates with a Master of Clinical Science (Complementary Medicine) from Southern Cross University in Lismore.

Mr Stewart, a former career dentist now living at Port Stephens on the state’s mid-north coast, said that at 97 years and 58 days, his fourth university degree may be his last.

“I can hang up my mortar board and academic robes after this one, although I said that after my last degree and then I got bored,” he said in a statement.

“I have so much time on my hands these days and I like to keep mentally active.”

The Sydney-born great-grandfather attained his first degree in 1936, when he graduated with a Bachelor of Dentistry with Honours from the University of Sydney.

He later completed a Doctor of Dental Surgery degree at Northwestern University in Chicago, and practised as a dentist in London, Sydney and Coonabarabran in rural northern New South Wales.

Mr Stewart set a Guinness World Record title at age 91 when he completed a law degree at the University of New England.

He said fitness and having a focus in life was a key to his longevity and intellectual stimulation.

“People should never use the excuse that `I am too old to study’ or `I have left my run too late’,” he said.

“It is never too late to expand your mind, make new friends and challenge yourself to achieve something worthwhile.”

Dr Sonya Brownie, one of Mr Stewart’s supervisors at Southern Cross University, said she was impressed by his commitment and enthusiasm.

“His willingness to embrace new learning technologies and his competency using different online learning applications is truly incredible,” she said.