K-ferrierite co-exchanged with Pt and In (PtIn(ferrierite)), with different pretreatments, is characterized by EXAFS (extended X-ray absorption fine structure), TDPAC (time differential perturbed angular correlation), TPR (temperature-programmed reduction), and hydrogen chemisorption. The presence of different In and Pt species is correlated with activity and selectivity during the NO selective reduction (SCR) with CH4 in the presence of excess oxygen. The reduction of PtIn(ferrierite) catalyst under controlled conditions (hydrogen at 350 or 500 degreesC) strongly promotes the activity of the said catalyst, The reduction at 350 degreesC results in the formation of small Pt degrees crystals, stable under wet reaction conditions, which probably favor both the oxidation of NO to NO2 and the adsorption of the said species, thus increasing the overall reaction rate. The reduction at 500 degreesC further increases the reaction rate because it promotes the formation of new (InO)(+) active species from the reduction of In2O3 at the catalyst external surface. Small crystals of Pt degrees are also formed when the calcined catalyst is treated under wet reaction conditions, thus increasing the reaction rate to an extent similar to the one observed for the catalyst reduced at 350 degreesC.