We studied photoluminescence (PL) properties of stoichiometric CuInSe2 (CIS) single microcrystals. Temperature and laser power dependencies of the PL spectra were measured. Two bands at 0.973 (A-band) and 0.991 eV (B-band) governed the obtained PL spectra. Measured dependencies showed very similar properties for both bands: the j-shift that was generated by altering the laser power was 2 meV per decade for both bands and thermal activation energies were 46 and 32 meV for A- and B-band, respectively. Based on these results, we assume that both bands come from the same shallow donor-shallow acceptor recombination process with different bandgap energies for CIS. The solid solution phase of CIS with K or Na is proposed as the source of distinctive bandgap. (C) 2003 Elsevier Science B.V. All rights reserved.