The optical properties of GaAs1-xSbx (5.9% <= x <= 9.7%) layers grown on GaAs substrates by gas-source molecular beam epitaxy were characterized by photoreflectance (PR) and piezoreflectance (PzR). Identification of conduction to heavy-hole (HH) band and conduction to light-hole (LH) band transitions originated from the strained induced valence band splitting have been achieved by comparing the relative intensities of PR and PzR spectra. The results indicate increases of the valence band splitting with increasing of Sb content. The temperature dependences of near band edge transition energies were analyzed using Varshni and Bose-Einstein expressions in the temperature range from 15 to 300K. The parameters that describe the temperature variations of the near band edge transition energies and broadening function were evaluated and discussed. (C) 2010 Elsevier B.V. All rights reserved.