Propane oxidative dehydrogenation has been studied at 350-500 degreesC, 1.0 bar and feed flow rate of 75 cm(3)/min over several supported chromium oxide-based catalysts. Effects of various chromium loadings, different supports, catalyst precursors and reaction conditions were investigated in an attempt to select an optimum catalyst for the reaction. Chromium oxides of different loadings ranging from 0.1 to 20 wt.% on gamma-Al2O3 were tested. At 450 degreesC, 10 wt.% loading exhibited propane conversion of 19%. gamma-Al2O3 gave the best performance when MgO, TiO2, SiO2 and gamma-Al2O3 were tested as supports. As a precursor, Cr(NO3)(3).9H(2)O exhibited the best results compared with K2Cr2O7, CaCr2O7, Na2Cr2O7, Cr2SO4.12H(2)O and CrO3. Effects of reaction temperatures and feed compositions were also evaluated on a 10 wt.% Cr-Al-O catalyst. The maximum selectivity to propene obtained was 61% while the yield was 18%. The 10 wt.% Cr-Al-O catalyst was characterized by X-ray diffraction patterns (XRD), temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) which confirmed the presence of both Cr3+ and Cr6+ in the calcined catalyst and, also, the predominance of Cr3+ in the spent catalyst. (C) 2003 Elsevier Science B.V. All rights reserved.