Elementary reaction of CCI radical with oxygen molecule has been investigated by time-resolved Fourier transform infrared emission spectroscopy. Product of CO was observed. The rate constant of this reaction is measured to be 2.6(0.4) x 10(-12) cm(3) molecule(-1) s(-1). It is found that the nascent product of CO is highly vibrationally excited with an average vibrational energy of 17-18 kcal mol(-1). DFT calculations at the B3LYP/6-311G(d) level reveal the reaction mechanism to be mainly a barrierless addition of 0, to CCI leading to a peroxide intermediate IMI (CICOO). The chain-like IMI breaks its O-O bond and Cl-C bond sequentially, forming the product of CO. (c) 2007 Elsevier B.V. All rights reserved.