The effects of H irradiation on the optical properties of GaAs 1-y N y epilayers in the dilute N limit have been studied. H irradiation leads to a progressive and finally complete passivation of bound exciton levels related to N complexes. A further thermal annealing restores the optical properties that the samples had before hydrogenation. These results are accounted for by the formation of N-H complexes with different bond strengths and dissociation energies.