The actor and musician told Metro that he likes being introduced to his sci-fi followers by their wives.
Asked if he has slept with any Doctor Who or Torchwood fans, he said: "No, never. But there's always a cute 27 or 35-year-old. The best is when women bring their husbands up and say, 'My husband thinks Captain Jack's fantastic'.
"And the husband says, 'John, if I was ever to do it with a bloke then you'd be the one'. And I'm like, 'Call me. You are hot'. But no, I've never done it. I have a partner. Plus, maybe I won't live up to their expectations."
Of how his TV fans differ from his music followers, he added: "They're all geeks and nerds. And I say that with love because I'm a nerd myself: I wear superhero T-shirts; I go to Comic-Con; I buy all the memorabilia."
Barrowman recently said that he would like to return to Doctor Who for the show's 50th anniversary in 2013.
> 'Torchwood' John Barrowman: 'I'm no party animal'
Watch the John Barrowman 'All Out Of Love' music video below: