Nascent products Of C2H3 + O-2 reaction have been studied by time-resolved FTIR emission spectroscopy. Vibrational excitation of reaction products H2CO, HCO, CO, and CO2 was observed, providing the evidence of existing two exothermic reaction channels: HCO + H2CO and CH3 + CO2 for the reaction. The latter channel was firstly observed in the experiment. Simulation of the spectrum of the products reveals that the highest excitation of CO and CO2(nu(3)) at 5 mus is nu = 4 and 6, respectively; the branching ratio of the channel HCO + H2CO to the channel CH3 + CO2 is estimated to be 17. (C) 2002 Published by Elsevier Science B.V.