An apparatus for making recorded kinetic measurements on reacting systems involving gases and solids or liquids has been constructed and tested by studying the decomposition of benzene diazonium chloride. In operation, helium is flowed through one side of a thermal conductivity detector (TCC), an equilibration tube containing solvent (if necessary), through the reactor, and back through the other side of the TCC. The measurement is made under conditions of programmed ambient temperature. The resulting recorder pen displacement is proportional to the concentration of gas in the helium stream, and, with appropriate apparatus design, to the rate of evolution of nitrogen. The skewed bell curve which results can be analyzed for the kinetic data. At each temperature (time) the pen displacement is a direct measure of the reaction velocity. The measurement has thus resulted in a transformation from a differential to an algebraic kinetics expression. The area under the curve to any temperature (time) is proportional to the total amount of gas produced. In a calibrated apparatus, one thus has a continuous analysis of the reaction. Treatment of the data to obtain an Arrhenius expression is a fairly straightforward procedure, programmable for computer solution. The example of reaction chosen is the decomposition of benzene diazonium chloride. The results are compared with literature values.