We report the results of our studies of optical and electro-optic properties of GaInNAs/GaAs single quantum wells grown by chemical beam epitaxy. The quantum wells have been characterised by scanning transmission electron microscopy and energy dispersive X-ray analysis. Photoluminescence measurements from sequentially grown GaInAs and GaInNAs quantum wells were carried out between 4 K and room temperature. A significant difference in the temperature dependence of GaInNAs band gap compared to nitrogen-free GaInAs is observed. Photoluminescence results are used to determine the interband transition energies. The results are compared with the theoretical values obtained using the band-anticrossing model. When the device is illuminated with monochromatic light, a finite photovoltage develops in the plane of the quantum wells due to Fermi level fluctuations. (C) 2002 Elsevier Science Ltd. All rights reserved.