The catalytic activity and selectivity of CrOx/SiO2 for the dehydroisomerization of n-butane were studied at 550 degrees C and 1 atm. Influence of chromia concentration and chromia precursor on the oxidation state, activity and selectivity were investigated. The catalysts were characterized by X-ray diffraction (XRD), TGA and temperatures programmed reduction (TPR). The isomerization activity linearly increased with increasing acidity and Cr loading. The addition of chromium precursors in complex form decreased the initial activity in dehydroisomerization of n-butane and but increased the selectivity of butenes. Catalyst, which had the highest acidity and lowest crystallite size, was the most active in isomerization reaction. The highest selectivity and yield of butenes achieved was 92% and 5.5%, respectively. (C) 2008 Elsevier B.V. All rights reserved.