Infrared diode laser spectroscopy was used to probe the kinetics of the NCCO + O-2 reaction. Several NCCO transitions were detected at 1887 -1890 cm (1), in good agreement with a recent high-level calculation for the nu(2) fundamental vibrational frequency. The total rate constant of the NCCO + O-2 reaction was measured to be (5.2 +/- 0.5) x 10 (13) cm(3) molecule (1) s (1) at 2 Torr pressure of N-2. The NCO + CO2 product channel was detected for the first time by probing (OCO)-O-18-O-16 products from NCCO + O-18(2). The branching ratio for this channel was estimated to be 0.28 +/- 0.06 at 3.2 Torr total pressure. (C) 2010 Elsevier B.V. All rights reserved.