Al2O3 and SiO2 were used to load chromium oxides with incipient-wetness impregnation method. These supported chromia catalysts were evaluated for the dealkylation of C10+ heavy aromatics in hydrogen flow and were characterized with BET, XRD, FT-IR, UV–vis DRS and H2-TPR techniques. The results indicate that the catalytic activity of supported chromia catalysts on SiO2 is higher than that of on Al2O3. Structural characterization results show that surface reduced CrOx species are the active sites for hydrodealkylation of C10+ heavy aromatics. (C10+ heavy aromatics denote the aromatics whose carbon numbers are equal to or greater than 10.) The structural models of CrOx species on the Al2O3 or SiO2 support surface were also proposed.