Abstract: A process for preparing a catalyst material, includes the steps of: (a) providing a support material having surface hydroxyl (OH) groups, wherein the support material is ceria (CeO2), zirconia (ZrO2) or a combination of thereof; (b) reacting the support material having surface hydroxyl (OH) groups of step (a) with a precursor containing two transition metal atoms, each chosen independently from the group consisting of: W, Mo, Cr, Ta, Nb, V, Mn; (c) calcining the product obtained in step (b) in order to provide a catalyst material showing dual site surface species containing pairs of transition metal atoms derived from the precursor that are present in oxide form on the support material. Additionally, a catalyst material is obtained by the process set out above, and the catalyst material is used as an ammonia selective catalytic reduction (NH3-SCR) catalyst for nitrogen oxides (NOx) reduction.