AgInSRxS2-x (x=0-0.2) polycrystalline thin films were prepared by the spray pyrolysis technique. The samples were deposited on glass substrates at temperatures of 375 and 400 degrees C from alcoholic solutions comprising silver acetate, indium chloride, thiourea and tin chloride. All deposited films crystallized in the chalcopyrite structure of AgInS2. A p-type conductivity was detected in the Sn-doped samples deposited at 375 degrees C, otherwise they are n-type. The optical properties of AgInSnxS2-x (x < 0.2) resemble those of chalcopyrite AgInS2. Low-temperature PL measurements revealed that Sn occupying an S-site could be the responsible defect for the p-type conductivity observed in AgInSRxS2-x (x < 2) thin films. (c) 2005 Elsevier B.V. All rights reserved.