The effects of hydrogenation on GaAlAs layer grown by molecular beam epitaxy stored over a long period of time was investigated using photoluminescence (PL) measurement. Upon hydrogenation, the defects in the GaAlAs are passivated and the PL intensity increased many times. Hydrogenation changes the energy of the defect produced on storage of GaAlAs and new features appear in excitonic emissions. On annealing the hydrogenated GaAlAs at temperatures ≳500 °C, the defects are depassivated and the PL intensity degraded. Hydrogenation improves the PL intensity of emission from a stack of GaAs/GaAlAs quantum wells (QW) of different well widths by a factor which varies with the depth of the QW from the surface. ©1995 American Institute of Physics.