The impact of nitroxy-substituents, -ONO2, on the dominant chemical reactions in the atmosphere is still not fully understood. A theoretical DFT and coupled cluster theory analysis of alkyl radicals with nitroxy-substituents on the radical carbon revealed that such radicals are unstable, dissociating by O-N bond scission and leading to a carbonyl compound and NO2. This dissociation occurs sequentially after completion of the reaction forming the alpha-nitroxy-substituted alkyl radical, such that the formation process is independent of the subsequent O-N bond scission. The presence of a beta-nitroxy substituent in alkoxy radicals decreases the barrier to decomposition by 12 kJ mol(-1). (C) 2008 Elsevier B. V. All rights reserved.