The product branching ratio of the HCCO + NO reaction was investigated using the laser photolysis/infrared absorption technique. Ethyl ethynyl ether (C2H5OCCH) was used as the HCCO radical precursor. Transient infrared detection Of CO, CO2, and HCNO products was used to determine the following branching ratios at 296 K: φ(CO+HCNO) = 0.78 ± 0.04 and φ(CO2+HCN) = 0.22 ± 0.04. These values are in good agreement with some recent ab initio calculations.