The kinetics of the NCCO + NO2 reaction was studied by transient infrared laser absorption spectroscopy. The total rate constant of the reaction was measured to be k = (2.1 +/- 0.1) x 10(-11) cm(3) molecule(-1) s(-1) at 298 K. Detection of products and consideration of possible secondary chemistry shows that CO2 + NO + CN is the primary product channel. The rate constants of the NCCO + CH4 and NCCO + C2H4 reactions were also measured, obtaining upper limits of k (NCCO + CH4) <= 7.0 x 10(-14) cm(3) molecule(-1) s(-3) and k (NCCO + C2H4) <= 5.0 x 10(-15) cm(3) molecule(-1) s(-1). Ab initio calculations on the singlet and triplet potential energy surfaces at B3LYP/6-311++G**//CCSD(T)/6-311++G** levels of theory show that the most favorable reaction pathway occurs on the singlet surface, leading to CO2 + NO + CN products, in agreement with experiment.