Singapore swimmer Joseph Schooling said Tuesday he was contemplating a professional career in the United States after winning the city-state's first ever Olympic gold medal with a stunning win over Michael Phelps.

The 21-year-old Asian champion set an Olympic record of 50.39sec in Rio last week after edging out his American idol Phelps, the most decorated Olympian in history, in the men's 100m butterfly final.

"I'm going to finish my education up in UT (the University of Texas), get my diploma, and then we can talk about turning pro, that's the plan," the sophomore told AFP in an interview on Tuesday.

Schooling said he would prefer to be based in the United States, where he would be able to focus on training at a high level.

"I imagine it'll be super hard for me to live in Singapore and train and perform... I just think in the US, I'm more suited, or I'm more used to the US training style now, the environment and everything," he said.

"I've got a good thing going, why change it?"

He now has his sights set on breaking the 100m butterfly world record of 49.82sec set by Phelps in Rome in 2009.

The record was set before the world swimming governing body FINA banned swimsuits made with polyurethane, a material that reduces drag in the pool.

"A lot of those super suit world records haven't gone down, but I think swimming's evolving," Schooling said.

"Swimmers, human beings, they're evolving together, getting stronger, fitter, better nutrition, more sports science... time's definitely on my side and I think I have enough time to drop half a second more."

Schooling is also looking to add to his programme the 200m butterfly and the 200m individual medley, in addition to the 100m freestyle and 100m butterfly.

After resuming training in two weeks, he is looking to win at the World Championships in Budapest next year.

Schooling on Monday returned to a rapturous welcome in Singapore where hundreds turned up at Changi Airport before dawn to greet him.

Prime Minister Lee Hsien Loong invited Schooling and his parents to parliament where he received a standing ovation after a motion was passed to formally congratulate him.

Schooling also won a four-year exemption from mandatory military service so he can prepare for the Tokyo 2020 Olympics, where he is expected to peak.

He already had a three-year deferment ending after Rio 2016, but his sensational performance made another extension a formality.

Schooling's mixed European and Asian heritage has resonated strongly in the immigrant society of 5.5 million people, which had to rely on naturalised athletes for years to win medals at international events until the homegrown swimmer emerged as a world-class competitor.

He will also receive Sg$1.0 million in prize money as part of a programme aimed at encouraging school-obsessed young Singaporeans to excel in sport.