Cu/TiO(2), Fe/TiO(2) and heteropoly acid promoted Cu/TiO(2), Fe/TiO(2) catalysts were prepared and characterized by N(2) physisorption, XRPD, NH(3)-TPD, H(2)-TPR and EPR. The catalysts exhibited only crystalline TiO(2) phases with the active metals and promoters in highly dispersed state. The acidic properties were studied and compared with the catalytic activity for the selective catalytic reduction (SCR) of NO with ammonia. The SCR activities and acidity values of heteropoly acid promoted catalysts were found to be much higher than unpromoted catalysts. The influence of potassium poisons on the SCR activity and acidity was lower for promoted catalysts than for unpromoted catalysts. In the heteropoly acid promoted catalysts the SCR active Cu and Fe metals were protected from potassium poisons by bonding of the potassium to the Bronsted acid centres. Thus heteropoly acid promoted catalysts might be suitable for biomass fired power plant SCR applications. (C) 2011 Elsevier B.V. All rights reserved.