High resolution infrared diode laser kinetic spectroscopy has been used to investigate the properties of C\sb2H reaction kinetics. The ethynyl radical (C\sb2H) was produced in a flowing system by excimer laser photolysis (ArF, 193 nm) of either CF\sb3CCH or C\sb2H\sb2 and the transient infrared absorptions of C\sb2H or possible reaction products were followed with the diode laser probe. The kinetics of the C\sb2H + O\sb2 reaction were studied with a goal of determining the reaction products. Only two reaction products were observed, CO and CO\sb2, with the amount of CO produced being about five times larger than the amount of CO\sb2 produced. Both products are produced in vibrationally excited states. CO\sb2 was produced long after C\sb2H reacted and thus is not a product of the direct reaction. Two processes leading to CO formation have been observed: a fast, direct process for which the rate of CO appearance approximately matches the rate of C\sb2H decay and a much slower indirect process. The fast process produces vibrationally excited CO (v = 5 ← 4 and higher). The indirect process is observed to be dominant for the lower vibrational transitions and its rate exhibits saturation with increasing O\sb2 pressure. In order to approximate these kinetics, it appears that at least two intermediates between C\sb2H and CO must be involved for the indirect process. In other kinetic studies, the rate constants of C\sb2H reactions were measured to see if other C\sb2H reactions might exhibit addition channels. The time decay of a C\sb2H infrared absorption line originating from the ground vibronic state was monitored as a function of reactant pressure to determine a second order rate constant. When possible the dependence of the reaction rate on helium pressure was investigated over the range of 8-70 Torr. Second order rate constants of 3.0(2) × 10\sp−12, 1.3(3) × 10\sp−10, 3.6(2) × 10\sp−11, 4.4(4) × 10\sp−13, 2.3(3) × 10\sp−13 cm\sp3 molecule\sp−1 s\sp−1 were obtained for the reactions of C\sb2H with CH\sb4, C\sb2H\sb4, C\sb2H\sb6, H\sb2 and D\sb2 respectively. A third order rate constant of 2.1(3) × 10\sp−30 cm\sp6 molecule\sp−2 s\sp−1 was obtained for the reaction of C\sb2H with CO.