The effects of the passivation of defects in polycrystalline nitrogen-doped cuprous oxide (Cu2O) thin films with hydrogen or cyanide treatment were studied. In the photoluminescence (PL) measurements, although the emission was not observed before treatment, luminescence of Cu2O at around 680 nm was observed after each treatment. This improvement in the luminescence property may be due to the passivation of non-radiative recombination centers by H or CN. The hole carrier concentration increased from the order of 10(16) to 10(17) cm(-3) With hydrogen or cyanide treatment. From these results, both the hydrogen and cyanide treatments were found to be very effective to passivate defects and improve the optical and electrical properties of polycrystalline Cu2O thin films. The thermal stability of the passivation effects by the cyanide treatment is, however, superior to that by the hydrogen treatment. (C) 2003 Elsevier Science B.V. All rights reserved.