SnO2-ZrO2 nanocomposite catalysts with different compositions ranging from 0 to 100% of SnO2 were prepared at room temperature by co-precipitation method using aqueous ammonia as a hydrolyzing agent. X-ray diffraction, transmission electron microscopic characterization revealed the SnO2-ZrO2 nanocomposite behavior. Acid-base properties of these catalysts were ascertained by temperature-programmed desorption (TPD) of NH3 and CO2. Both acidic and basic sites distribution of the nanocomposite catalysts is quite different from those of respective single oxides (SnO2 or ZrO2). Catalytic activity of these nanocomposite catalysts for ethylbenzene dehydrogenation (EBD) to styrene in the presence of excess CO2 was evaluated. The change in the acid-base bi-functionality of the nanocomposite catalysts in comparison with single oxides had profound positive influence in enhancing the catalytic activity. (c) 2007 Elsevier B.V. All rights reserved.