Chrome-doped Mn3O4 thin films were grown on the glass substrates by the spray pyrolysis technique at 350 degrees C. XRD diffraction and Raman spectroscopy analysis revealed that all samples have tetragonal spinel structure with a preferred orientation along the direction (1 0 1). Absorption coefficient has been measured using both transmission and mirage effect. The band gap energy decreases from 2.2 to 1.9 eV with Cr content while Urbach energy value increases from 354 to 473 meV. Also, thermal conductivity was evaluated. Finally, physical properties have been evaluated and discussed in terms of alteration of the band gap edges, electrical patterns and mirage effect. (C) 2015 Elsevier Ltd. All rights reserved.