A mass spectrometer was used in conjunction with a discharge-flow system to study the reactions of hydrogen, oxygen and nitrogen atoms with nitrosyl chloride, and of hydrogen atoms with cyanogen. For each of the nitrosyl chloride reaction systems, a rate constant was obtained for the primary reaction, the products and intermediates were identified, and the overall stoichiometry was determined. From this information a detailed mechanism for the reaction was deduced. In the cyanogen study, the order and rate constant for the primary reaction were determined. The measured rate was used to estimate the heat of format ion of the CN radical.