InP samples, which had received a capless anneal in a phosphine/hydrogen atmosphere, were examined for hydrogen contamination by secondary‐ion mass spectrometry. It is found that hydrogen accumulates at the InP surface during annealing. Annealing of Be‐implanted InP leads to similar profile shapes for the Be and H atoms. Passivation of the Be acceptors, if effective at all, appears to be of only minor significance.