Ag/Al2O3 catalysts prepared from boehmite needles (ca. 10 nm x 100 nm), which were formed by a hydrolysis of aluminium tri-isopropoxide (AIP), showed good performances for selective catalytic reduction of NOx compared with the previously reported catalysts [N. Aoyama, K. Yoshida, A. Abe, T. Miyadera, Catal. Lett. 43 (1997) 249], especially when ethanol is employed as a reducing agent in the presence of water. Temperature programmed reduction (TPR) study revealed that the Ag species are attractively interacted with the alumina surface and the oxidized Ag species contribute positively for the improvement of the catalytic activity at the temperatures above 750 K. It is concluded that the boehmite needles as a precursor of alumina support are useful to create the catalytically active sites for NOx reduction.