The effect of Mg substitution on the structural, morphological and electrical properties of sprayed magnesium cobalt oxide (MgxCo3-xO4) thin films (0 ≤ x ≤ 1) have been studed using X-ray diffraction (XRD), scanning electron microscopy (SEM), compositional analysis with EDS technique and four probe method for the electric conductivity measurements. XRD evaluation exhibits that MgxCo3-xO4 thin films are polycrystalline with spinel cubic structure. The EDS study confirms the presence of Mg and Co in the substituted films with the same concentrations as in the starting solution confirming the formation of MgxCo3-xO4 thin films. The effect of temperature on the dc conductivity reveals that the electrical transport mechanism in MgxCo3-xO4 thin films is based on the three-dimensional Mott’s variable-range hopping model. The density of states, the hopping distance, and the hopping energy have been successfully evaluated.