The remote hydrogen plasma passivation of semi‐insulating InP substrates has been investigated byinsituspectroscopic ellipsometry (SE), to characterize the changes of InP morphology, andexsituphotoluminescence (PL) to reveal the passivation effect of nonradiative centers operated by H atoms. The concurrence of the InP native oxide removal without surface damage (phosphorus ablation) and the passivation by H‐atoms results in a remarkable enhancement of the PL intensity. ©1996 American Institute of Physics.