A series of Ni-doped HZSM-5 catalysts were prepared and the catalytic performance of these catalysts in n-butene trimerization was investigated. The Ni-loading, the Si/Al ratio of HZSM-5 and the reaction conditions (temperature, pressure and WHSV) played great influences on the catalytic performance of these catalysts in the reaction. 77.5 wt.% conversion of n-butene and 50.5 wt.% selectivity of trimers as well as 19.6 x 10(-2) g(trimers/) (gcat h) yield of trimers were obtained on 1 NiHZSM-5(320) catalyst up to 148 h at 420 degrees C, WHSV = 2 h(-1) and 1.0 MPa. In addition, the physicochemical properties of these catalysts were comparatively characterized by powder X-ray diffraction (XRD), N-2 isothermal adsorption-desorption, infrared red spectroscopy (IR) and pyridine adsorbed infrared red spectroscopy (Py-IR) techniques. The doping of Ni into HZSM-5(320) modified the specific surface area and the acidity of these catalysts. which in turn affected the catalytic performance of these catalysts in n-butene trimerization. The acidic amount and the ratio of Lewis/Bronsted acid sites (L/B) on the external surface of these catalysts were close relative to the catalytic performance of these catalysts. I NiHZSM-5 (320) catalyst showed the highest catalytic performance in n-butene trimersization among the investigated catalysts because it had the proper acidic amount and the proper L/B ratio on its external surface. (C) 2009 Elsevier B.V. All rights reserved.