Catalysts of iron oxide dispersed on Al or Si oxides were prepared via a polymeric precursor derived from the Pechini method and tested in the dehydrogenation of ethylbenzene in the presence of CO2, in order to contribute with the studies of this reaction. The catalysts were characterized by thermogravimetric analysis (TG), temperature-programmed reduction (TPR), X-ray diffraction (DRX) and temperature-programmed desorption of CO2 (TPD-CO2). Analysis of the spent catalysts by TG and Fourier transformed infrared spectroscopy (FT-IR) pointed to the contribution Of CO2 to the coke deposition. The catalytic results suggest that the high initial ethylbenzene conversion is due to the contribution of basic sites, and the CO2 adsorption in the basic site (lattice oxygen) may compete with the oxidative dehydrogenation of ethylbenzene. Although CO2 provides the appropriate conditions to lower the consumption of the basic site, it is not able to promote the Fe2+ oxidation or to regenerate the basic site (lattice oxygen) in the iron oxide dispersed on Al or Si oxide catalysts. (C) 2009 Elsevier B.V. All rights reserved.