The radical-radical reaction of formyl radical with chlorine atom has been investigated by the time-resolved infrared emission spectroscopy and by the theoretical calculations at the UB3LYP/6-31++G(d,p) and single-point UCCSD(T)/6-311++G(d,p) levels. The products have been verified as the vibrationally excited CO (upsilonless than or equal to4) and HCl. The reaction is initiated by radical-radical recombination forming an intermediate of formaldehyde chloride, which further dissociates into the products of HCl and CO. (C) 2004 Elsevier B.V. All rights reserved.