Normally I'd say "on behalf of" is the only correct form, but I checked: "in behalf of" is also used! On behalf of... = acting in place of someone; to represent someone (or a group). "I talked to his boss, on his behalf." In behalf of... = it's not very common, but it means "for the benefit of someone/something"

i agree with annie lynn this one will do.. On behalf of somebody and also in behalf of somebody (American English) are used in two meanings: a) instead of someone, or as their representative: On behalf of everyone here, may I wish you a very happy retirement. b) because of or for someone: Oh, don’t go to any trouble on my behalf. ... The "in" is not used in the construction "in behalf of" — not that I'm aware of, anyway. It's used in sentences like "He will act in your behalf." ^ㅅ^

I believe correct one is "On behalf"