The Mo/SnO2 catalyst was prepared by the impregnation method and characterized by thermal analysis, X-ray diffractometry, diffuse reflectance infrared (DRIFT) spectroscopy as well as N-2 adsorption/desorption (BET method) techniques. The results permit to infer that the highly dispersed Mo ions strongly affect SnO2 crystallization forming only MoO3 and SnO2 phases. Moreover, the thermal behavior of Mo/SnO2 showed the dissolution of MoO3 in SnO2 crystals at temperatures above 750 degrees C. Nevertheless, reduced MoO3/SnO2 presented marked activity and selectivity towards CH4 decomposition at 700 degrees C so as to forming a formaldehyde intermediate but rather favored the formation of CO2.