We have investigated the optical properties of GaInNAs/GaAs single quantum wells grown by metalorganic vapor-phase epitaxy on misoriented GaAs substrates with the use of photoluminescence (PL) spectroscopy sensitive to localization of carriers and photoreflectance (PR) spectroscopy sensitive to the intrinsic band-edge transition. We have found from systematic results of PL spectra, PL-decay profiles and PR spectra that the band-edge energy of the quantum well is lowered with increasing offset angle from 2 degrees to 15 degrees toward (111)A and that the localization of carriers due to disorders of the band-edge state is enhanced. (c) 2006 Elsevier B.V. All rights reserved.