Reaction performance, acidic and basic properties, as well as reduction properties of various supported molybdenum catalysts for the metathesis of ethylene and butylene-2 to propylene were investigated by TPR and NH3-TPD techniques in a flow-reactor. Besides temperature, space velocity and pressure, the stability of a Mo/(Hbeta-Al2O3) catalyst is strongly affected by the Mo loading, the calcination temperature and the hydrothermal treatment conditions. A suitable molybdenum loading on HP-Al2O3 is favorable to the stability of the catalyst that possesses suitable amount of acidity, which was determined by NH3-TPD measurements. The optimum preparation conditions of the Mo/(HP-Al2O3) catalyst are as follows: molybdenum content 3 wt.%, hydrothermal treatment and calcination at 550degreesC for 2 h and 700degreesC for 2 h, respectively. Thus, the optimal catalyst of 3Mo/(Hbeta-Al2O3), designated as 3Mo/HP5502700, could keep a conversion of C4H8-2 at about 82% during 22h of reaction time-on-stream under the following conditions: N-2/C2H4 = 1.5, C2H4/C4H8-2 = 3/1, WHSV(C2H4 + C4H8-2) = 1 h(-1), T = 120degreesC, and P = 1.0 MPa. In addition, a suitable pressure, such as 0.5-1.0 MPa, and a low temperature, such as 35degreesC, are beneficial for keeping the stability of the 3Mo/HP5502700 catalyst. (C) 2004 Elsevier B.V. All rights reserved.