The interview is in full below.
BEWARE!!! SOME SERIOUS DALEK INNUENDO!!!
How is Torchwood different to Doctor Who?
Because it's for a completely different audience. It's on after the watershed and it's for adults, or teenagers who have permission from their parents to watch this type of show.
I'm not just saying it's more risque, but we're dealing with violence. There's blood, there's gore, there's sex.
So if parents let their kids watch it, they must understand they'll have some explaining to do.
Writer Russell T Davies says your character has a "real life with a mortgage to pay and plenty of chips to eat". What else does he do?
He saves the world! He battles aliens and travels through time! That's what makes him exceptional. Someone described him as being the closest thing we've got to being a superhero. He doesn't have special powers, but he's a science-fiction action hero.
Is it really a respectable job to get up in the morning and fight aliens in a spaceship?
It absolutely is, and it's really respectable not only to get up and fight aliens and have a spaceship and shoot guns, but I also get to have sex, so that's good!
How complicated is Captain Jack's love life?
I joke about it a lot, but it's not complicated at all. It's very straightforward, very normal. But that's why I say about the whole kids thing. Not every nine-year-old has the ability to comprehend why this alien is having sex with somebody on the counter of a sink and then killing him.
Will Captain Jack be appearing in Doctor Who again?
I will be going back into Doctor Who right after I'm done with Torchwood. I think I'll be in three or four episodes.
You've lived and worked in both the UK and US - which do you call home?
The UK is my home. At the moment, I'm spending all my time in Cardiff. My partner [architect Scott Gill] is in London with his job and so he comes to Cardiff on the weekends.
I'm a huge fan of the city. The people are lovely - we have never had any complaints when we're filming in people's neighbourhood or when we close down their road. The city is hugely proud of the series and we're very proud to be there.
You've been quoted in the press as saying you want to adopt a child. Have you asked Madonna for advice?
I do not know Madonna, so the answer is no. What she does is her business. But Scott and I have talked about adoption, and I'm saying right here and now that we are not actively pursuing that at the moment.
You were passed over for the role of Will in the comedy series Will and Grace - how close did you come to getting the part?
I was of one of quite a few who got down to the last choices, and I was actually told that I wasn't gay enough - even though Eric McCormack is straight. Go figure!
As the star of cult movie Shark Attack 3, what would your advice be to anyone who's attacked by a shark?
Get the hell out of the water! Punch the s*** out of it! The shark I was dealing with was actually the old Jaws shark, so it was just a fake. I didn't learn any lessons - just to stay clear of them!
You've acted with aliens, sharks, Billie Piper and Yasmine Bleeth. Who's been the worst to work with?
Sharks are the worst and I have to say aliens are the best.
Any particular favourite?
I love the Daleks. They still scare the crap out of me when I'm on set and they still give me a thrill when I see them on television.
Have you been tempted to get inside one?
Captain Jack might have been inside a Dalek and a Dalek might have been inside Captain Jack!
But I have been inside the Dalek costume. And one day, while Billie [Piper] and I and Christopher Eccleston were filming, I picked up the microphone that controls the Dalek's voice and I started singing There's No Business Like Showbusiness.
Maybe there's a musical in there?
You never know! Lord of the Rings has been turned into a musical, so why not Torchwood?
John Barrowman talked to BBC News entertainment reporter Mark Savage.