Can we still get married in a catholic church without his christening certificate?

U will need the proof.......... also not just the certificate. i think he will need to fulfill all the sacerments. like communion and confirmation. Did he have these? if he has proof he did any of these then tell him to use this instead. but to get this saceremtn of marriage........u at least need to have communion and confirmation. He can, however, take adult cles to obtain this. its easy and not hard at all. I also think you will need to have the same cles being u were not catholic and didn't have the same sacraments. good luck