AgInSnS4 thin films were prepared by adding a tin salt to the starting solution used for preparing chalcopyrite AgInS2 thin films by spray pyrolysis The AgInSnS4 films were grown at substrate temperatures in the 300-400 degrees C range, using an alcoholic solution comprised of silver acetate, indium chloride, tin chloride and thiourea. The tin chloride content in the starting solution was gradually varied in terms of the molar ratio x = [Sn]/([S] + [Ag]) from 0 to 0.5 to obtain Sn-doped chalcopyrite AgInS2 (x < 0.2) and spinel-like AgInSnS4 (x = 0.2-0.4). X-ray diffraction studies indicated that AgInSnS4 has a cubic spinel-like structure with lattice parameter of 10.77 A. All AgInSnS4 thin films exhibited p-type conduction, and their room temperature conductivity ranged from 10(-1) to 10(-2) S/cm. The conductivity versus 1/T plots for this material showed an Arrhenius-like behavior, from which two activation energies of E-a1=0.23-0.40 eV and E-a2=0.07-0.20 eV were determined. These results suggest that the grain boundary scattering and the ionization of shallow acceptors dominate the charge carrier transport in the sprayed AgInSnS4 thin films. The AgInSnS4 absorption spectrum revealed an energy gap around E-g = 1.89 eV, which was associated to direct-allowed transitions. To our knowledge, the quaternary compound has been prepared for the first time using spray pyrolysis. (C) 2009 Elsevier B.V. All rights reserved.