Thin films of Cd(1-x)5Mg(x)Te with band gap in the range of 1.6-1.96 eV were deposited by vacuum co-evaporation of CdTe and Mg on glass substrates heated at 300 degrees C Different experimental techniques such as XRD. UV-vis spectroscopy, SEM, and XPS were used to study the effect of Mg incorporation into the lattice of CdTe. The band gap of the films showed a clear tendency to increase as the Mg content in the film is increased. The Cd(1-x)5Mg(x)Te films maintain all the structural characteristics of the CdTe, however, diminishing of intensity for the XRD patterns is observed due to both change in preferential orientation and change in atomic scattering due to the incorporation of Mg. SEM images showed significant evidences of morphological changes due to the presence of Mg. XRD, UV-vis spectroscopy, and XPS data confirmed the incorporation of Mg in the lattice of CdTe. The significant increase in band gap of CdTe due to incorporation of Mg suggests that the Cd(1-x)5Mg(x)Te thin film is a candidate material to use as absorber layer in the top-cell of a tandem solar cell. (C) 2011 Elsevier B.V. All rights reserved.