The objective of the present work is to investigate the expansion of steady, isentropic, one-dimensional flow of hydrocarbon- oxygen combustion products through a convergent -dirvergent nozzle.The study includes the development of three models. The first model assumes a frozen gas mixture composition. The second model assumes the equilibrium composition of the gas mixture. The third model considers the actual flow process for which the reactions controlling the mixture composition have finite rates (kinetic model). The continuity,' momentum, energy, and state equations are solved numerically along the longitudinal direction of the nozzle. The flow properties and species concentrations are determined for different equivalance ratios and combustion chamber pressures. The resluts of the present investigation indicate that the flow characteristics determined using the three models are almost identical in the convergent part of the nozzle. While a substational deviation is experinced in the divergent part recommending the use of the kinetic model for accurate simulation of a real flow problem.