In an interview for an American news channel, he said he was looking forward to having children, but he wouldn't reveal anything more and said he was bemused by the constant speculation about whether his wife was expecting.
William said: "It is quite strange reading about it, but I try not to let it bother me.
"But I'm just very keen to have a family and both Catherine and I are looking forward to having a family in the future."
When pressed if there was any news he would like to share, William said: "You won't get anything out of me. Tight-lipped."
He told interviewer Katie Couric that he was still deciding if he would take another tour of duty with the Royal Air Force, or leave the military to assume royal duties full time.
"I'm still trying to decide. It's a really difficult one because I really enjoy my time in the Air Force and I'd love to continue it," he said.
"But the pressures of my other life are building. And fighting them off, or balancing the two of them, has proven quite difficult.
"More importantly, I'd rather like to have children. So that's the key thing really."
He spoke tenderly about missing his mum, Princess Diana, and added: "I'm just very sad that she's never going to get a chance to meet Kate."