In2S3(1-x)O3x is known from preceding studies to have a bandgap varying continuously as a function of x, the reason why this solid solution is potentially interesting in the field of photovoltaics. In this work, we present results on oxidation of In2S3 by heating in air atmosphere, to obtain the desired material. The oxidation is accompanied by a mass loss due to the substitution of S by O atoms that is studied by means of thermogravimetric analysis. It appears that the temperature region in which the oxidation occurs is strongly dependent on the texture of deposited films. As-grown films deposited by chemical bath deposition are subjected to oxidation at lower temperature than materials characterized by a better crystallinity and larger crystallite size. X ray diffraction and scanning electron microscopy were used to get information on the compounds and the texture of films.