During the catalytic combustion of naphthalene, compounds other than CO2 are often obtained. These products, as polymerized polycyclic aromatic hydrocarbons, oxygenated aromatic compounds and benzene derivate compounds, are usually more toxic than naphthalene. At the present work it is shown a nanocrystalline cerium oxide prepared by a combustion method employing a proper ethylene glycol concentration that exhibits very high activity in the decomposition of naphthalene in the presence of air and, most importantly, a selectivity value towards CO2 of 100% for any range of conversions and/or temperatures used. In addition, it has been demonstrated that the amount of ethylene glycol employed in the synthesis of the catalyst is determinant to achieve the optimal catalytic performance. The catalytic results have been explained in terms of the amount of cerium oxide defects. (C) 2009 Elsevier B.V. All rights reserved.