The CN+CH 2 CO and NCO+CH 2 CO reactions were studied over the temperature ranges 296-567 K and 296-556 K, respectively, using time-resolved infrared diode laser absorption and visible laser-induced fluorescence spectroscopy. The total rate constant data were fit to the following expressions: k 1 (CN+CH 2 CO) = (2.37+/-0.5)x10 - 1 1 exp[552.6+/-97/T] and k 2 (NCO+CH 2 CO) = (1.71+/-0.27)x10 - 1 2 exp[713.2+/-56/T] cm 3 molecule - 1 s - 1 . Detection and quantification of CO product yields suggests that an addition-elimination mechanism producing CH 2 CN+CO or CH 2 NCO+CO dominates these reactions, and that hydrogen abstraction to produce HCN+HCCO or HNCO+HCCO is a minor or negligible product channel.