The potential energy surface for the reaction of O( P-3) with HCNO ( fulminic acid) has been studied using ab initio methods. Critical points were optimized at the DFT-B3LYP/ 6-311++ G( d,p) level of theory, combined with single point energy calculations at the CCSD( T)/6-311++G( d, p) level. Two key critical points were re-optimized at the CCSD( T)/6-31G( d, p) level, showing a slight entrance barrier for the reaction. The energetically accessible reaction paths from an HC(O) NO complex lead to H + CO + NO and HCO + NO products. The calculations are in qualitative agreement with previous experimental results. (c) 2008 Elsevier B. V. All rights reserved.