SiO2 supported Cr2O3 catalysts with varying Cr content have been prepared and are characterized by nitrogen adsorption, low temperature oxygen chemisorption (LTOC), X-ray diffraction (XRD) and electron spin resonance (ESR) techniques. Aromatization of isophorone is carried out on these catalysts. A good correlation obtained between the oxygen uptake and aromatization yield helped to identify the nature of the active species.