The low-lying electronic states (S-0, S-1, S-2, S-3, T-1, T-2, T-3) of formyl cyanide have been studied by the CASSCF, B3LYP, and MP2 calculations with cc-pVDZ or aug-cc-pVDZ basis set. The structural features and properties of these states have been characterized on the basis of structural optimizations and molecular orbital calculations. The relatively high barriers to the C-H and C-C bond fissions on the S-1 and T-1 pathways reveal that the S-1 or T-1 dissociation of formyl cyanide proceeds with little probability upon photoexcitation to the S-1 state. (C) 2003 Elsevier Science B.V. All rights reserved.