Crystalline tin oxide was prepared by using the method of thermal decomposition of stannic chloride pentahydrate. Decomposition process was studied by thermogravimetric analysis and differential scanning calorimetry. This precursor salt was thermally treated at 800 degrees C during 4 hours to obtain a crystallite size similar to the reference sample. The crystallite size obtained for the as-prepared sample was 25 nm. For comparison purposes Titania P25 from Degussa Co. (crystallite size of 30 nm) was used as the reference sample. The as-obtained sample was characterized by the X-ray powder diffraction technique and infrared spectroscopy. The results indicate that SnO2 was obtained in the crystalline cassiterite phase. N-2 physisorption measurements were carried out to determine the textural properties of the obtained SnO2. Methylene blue photodegradation in the presence of the SnO2 catalyst was evaluated in a preliminary way monitoring the absorbance spectrum after the UV irradiation experiments were done (lamp emitting at 254 nm).