High resolution color center laser kinetic spectroscopy has been used to study the kinetics and spectroscopy of free radicals. The radicals are produced in a flowing system by the excimer laser photolysis of stable precursors. The transient infrared absorptions of the radicals are monitored with better than 1 μs time resolution. Spectra of the ethynyl radical (C\sb2H), produced by photolysis of acetylene, were collected between 3000 and 3600 cm\sp−1 with a goal of identifying the CH stretching fundamental of the molecule. A number of new bands of C\sb2H and its carbon-13 analogue (\sp13C\sp13CH) were observed and rotationally analyzed. These bands include three C\sb2H bands of \sp2Σ\sp+ + ← \sp2Σ\sp+ symmetry, one C\sb2H band of \sp2Π ← \sp2Π symmetry, three \sp13C\sb2H bands of \sp2Σ\sp+ + ← \sp2Σ\sp+ symmetry, and one \sp13C\sb2H band of \sp2Π ← \sp2Π symmetry. A number of \sp13C analogues of \sp12C\sb2H bands were identified. However, no conclusive assignment has been made for the CH stretch. Two tentative assignment schemes are given for several of the bands. The kinetics of the C\sb2H + O\sb2 reaction were studied with a goal of determining the reaction products. OH radicals were determined to be a minor product of this reaction. Experiments designed to determine the relative importance of the hydrogen atom producing channel were inconclusive. In other kinetic studies, a high temperature furnace was constructed to determine the temperature dependences of the product channels of the NH\sb2 + NO reaction. The reaction was initiated by the photolysis of NH\sb3 in the presence of NO. The branching ratios of the OH and H\sb2O producing channels were determined at 26, 400, 700, and 925\sp∘C by comparison of the increase in OH and H\sb2O absorption signals with the decrease in an NH\sb3 absorption signal. Branching ratios were calculated from the raw signals by using the infrared cross sections of the molecules, measured in separate experiments. The branching ratio of the OH channel is 14% at room temperature and increases to 25% at 925\sp∘C. The total of the two channels (OH plus H\sb2O) accounts for 100% of the reaction at room temperature; however, this number drops to about 80% for higher temperatures, possibly indicating the onset of another channel.