Ni-Re-K/Al2O3 catalysts used in reductive alkylation of p-nitroaniline with 2-butanone were investigated by means of BET, XRD, H-2-TPR, NH3-TPD and pyridine-FTIR techniques. The results showed that the reducibility and the number of surface Lewis acidic sites of the catalysts played a significant role in improving their activities and selectivities. 10Ni-1Re-1K/Al2O3 (gamma-Al2O3 calcined at 1173 K) exhibited better reducibility and the proper amount of surface Lewis acidic sites, so it performed the highest selectivity towards N,N'-di-sec-butyl p-phenylene diamine among the catalysts. (C) 2007 Elsevier B.V. All rights reserved.