The location of cobalt and its interaction with platinum in Pt,Co-mordenite were studied using TPR, TPD and N-2 adsorption at varying pressures. The catalytic performance for the selective catalytic reduction (SCR) of NOx with CH4 was evaluated using a fixed-bed flow reactor. The effect of reducing, oxidizing, inert atmospheres upon the location of the extra-framework cations was also investigated. The bimetallic Pt,Co-mordenite catalyst showed better N2 Selectivity than the Co-mordenite. The TPR results indicated that more than 90% of the cobalt was located at hard-to-reduce ion exchange positions. The high-pressure DRIFTS experiments, designed to give information about the adsorbed N2, indicated that both {Co(OH)}(+) and Co2+ species were located in the main channels of the mordenite, while the residual Na+ and H+ were evenly distributed between the cation sites in the main channels and the side pockets. The small proportions of Pt-0 and Co-0 formed after reduction at 350 degreesC were in intimate contact and promoted the conversion of NO to NO2, which is a better oxidant for methane than O-2. (C) 2004 Elsevier B.V. All rights reserved.