The 'Bodies' popstar, who left the group in 1995, spoke about reuniting with former bandmates Gary Barlow, Mark Owen, Jason Orange and Howard Donald on Friday Night With Jonathan Ross.
When asked whether a reformation may happen, he said: "Yes I hope so."
He continued: "We've got together, done bits and bobs. I can't say much."
The singer was rumoured to have spent time in a New York studio with the 'Rule The World' group earlier this year. Barlow has also spoke frequently about his renewed friendship with the 35-year-old.
Williams, who is promoting new album Reality Killed The Video Star, performed upcoming single 'You Know Me' and 2002 hit 'Feel' on the BBC chatshow.