Cu(In,Ga)Se-2 semiconductor is widely used for solar cell applications and higher photovoltaic conversion efficiencies have been achieved with this material using US as a window layer. The recent studies demonstrated that the novel window layer, Zn1-xMgxO could be one of the best alternatives to CdS. Since this material has not been thoroughly investigated, an attempt has been made in this study to grow Zn1-xMgxO films by spray pyrolysis technique. The films were prepared on glass substrates at a temperature of 300 degrees C over the composition range, 0 <= x <= 0.4. The microstructural, electrical and optical properties of as-grown Zn1-xMgxO films were studied using appropriate techniques. The films showed a predominant (002) reflection corresponding to the hexagonal wurtzite structure. No changes in the preferred orientation with composition have been observed. The films prepared at x = 0.24 showed good crystallinity and surface morphology. The change in the physical properties like electrical resistivity, energy band gap and photoluminescence with 'Mg' composition in the films was evaluated. The results were reported and discussed. (c) 2007 Elsevier B.V. All rights reserved.