If the candidate doesn't have a experience in the current domain to which he is being interviewed,
I would suggest two options:

1) check whether he has done anything related to that particular domain. For (e.g) if the role he is being interviewed is related to web, ask him whether he had done anything realted to web, at least a static site. If that's the case you can conclude that he might be interested in working in that domain and you can consider there's a chance that he'll learn things over the course of time. But whether he gets hired or not depends on his attitude in the interview which should be decided by you as a interviewer. So it's your call.

2) If not, there comes the difficult choice. He might be interested to work inorder to save his financial hardships. But that doesn't justify the reason he'll be a good fit for the organization. So may be you can give him a chance to prove his interest by asking him to work on some kind of mini open source project and if he succeeds in that with in a span of time you gave, you can refer him back and take him. So you don't have to feel guilty nor the candidate.

The second choice is a polite way of rejecting the candidate at least for now. So that he'll learn. If he got the stuff even if it doesn't help him at this interview, at least by next interview he'll have something to showcase which will increase his chances of getting hired.

So in either case, he'll respect you. So does your company :)

Just my two cents.