Iron-containing composites were prepared and characterised by X-ray diffraction (XRD), thermoprogrammed reduction analyses (TPR), basicity measurements, textural properties, Raman spectroscopy, scanning electron microscopy coupled to EDX (SEM-EDX), thermoprogrammed oxidation analysis (TPO) and evaluated in the dehydrogenation of ethylbenzene with CO(2). The presence of either Ce or Co promoters greatly enhanced the catalytic activity of the solids in the dehydrogenation of ethylbenzene with CO(2), when compared to Sri and Mn analogues, due to their easy reducibility. The cobalt species (FeCo(2)O(4) and CoO(x)) in the CoFeSi catalyst determined the activity. Severe reaction conditions provoked the formation of amorphous carbon, and also graphitic species were observed. In addition, the reducibility of Co species may play a role in favouring the formation of hard carbonaceous deposits, as the redox process involved the Co and Fe species in the ethylbenzene and CO(2) environments. The investigation of temperature, CO(2)/EB ratio, W/F and space velocity for the most active solid showed that 550 degrees C, P = 1 atm, a CO(2)/EB ratio of 30, W/F = 2.5 g(cat) h mol(EB)(-1) and a space velocity of 3.4 h(-1) provided an EB conversion and styrene selectivity of about 15.3% and 99.6%, respectively. (C) 2011 Elsevier B.V. All rights reserved.