Cd1-x Mn x Te thin films were prepared by co-sputtering CdTe and Mn targets on to a variety of substrates at room temperature. The sputter powers of the CdTe and the Mn targets were fixed at 75 W and 65 W, respectively, and the influences of the substrate on the structural properties of the deposited thin films were investigated. All of the films were polycrystalline in nature, and X-ray diffraction showed that the lattice constant varied between 6.3912 and 6.4518 Ǻ depending on the substrate. The incorporated Mn mole fraction varied between 12.796% and 13.046%; this variation may be attributed to a change in the band-gap. The band-gap energy increased from 1.6767 to 1.6799 eV and the grain size decreased from 133 to 74 nm as the strain increased from 14.12% to 34.12% for the various substrates.