Optical characterization of InGaAsN layers on InP substrates grown by molecular beam epitaxy (MBE) was carried out using photoluminescence (PL) and photoreflectance (PR) measurements. The PL wavelength coincides well with the energy gap (E-g) obtained by the PR measurement for the samples grown with various nitrogen compositions and growth temperatures. In particular, the sample which has the longest PL wavelength (2.03 mu m at 300 K) shows a clear PR spectrum and the E-g obtained by the PR measurement corresponds well with the PL peak energy, indicating that the emission at 2.03 mu m is not a defect related emission but a band-edge emission of the InGaAsN layer. (C) 2008 Elsevier B.V. All rights reserved.