Cu-ion-exchanged titanium-pillared clays (Cu-Ti-PILCs) were prepared using ion exchange strategy under different pH values and used for selective catalytic reduction (SCR) of NO by propylene. The influences of pH value on the catalytic performance and the nature of copper species were investigated. The results of activity test showed that the highest conversion of NO into N-2 and the low-temperature activity increased with the increase of pH value up to 6, and then decreased with the further increase of pH value. The characterization results showed that the copper species were well dispersed over the prepared catalysts, and the different ratios of Cu2+/copper species existed over the studied catalysts. The Cu2+ species can enhance the low-temperature activity and the highest conversion of NO into N-2. Moreover, the highest conversion of NO into N-2 and low-temperature activity increased with the increase of the Cu2+/copper species rate. (C) 2011 Elsevier BM. All rights reserved.