The flow field inside a scramjet engine combustor involves complex phenomena such as fuel-air mixing, combustion chemistry, and flow separation. In order to determine the properties of the flow along the length of the combustor, mass, momentum and energy balance equations are solved simultaneously using a numerical method. While a full three dimensional computational simulation gives detailed results with high order of accuracy, it demands a great amount of time and computational resource. A low order analysis produces a fast overall picture of the combustor operation which in turn provides valuable information suitable for the preliminary design process. This research work aims to describe the analysis process of the scramjet combustor in which a quasi-onedimensional, multi-species, reacting real gas model of the flow is developed to address the limitations in previous researches. The Numerical Propulsion System Simulation (NPSS), into which the NASA Chemical Equilibrium with Applications (CEA) code is integrated, is utilized as the platform to perform the analysis. The analytical model is validated by comparison with experimental data from previous researches. The results obtained by this method are expected to shed some light on the advantages of using detailed chemistry with lower order analysis to calculate scramjet engine performance. v Table of Contents Acknowledgements .