The effect of reduced chemistry model on the numerical predictions of supersonic combustion of hydrogen in a model combustor is investigated. To this end, 3D, compressible, turbulent, reacting flow calculation with a reduced chemistry model (with 7 reactions and 7 species) has been carried out. The results are compared with earlier results obtained using the single step chemistry and detailed chemistry model. Staged injection is considered to evaluate the capability of the reduced chemistry model. Predictions of mass fractions of major species, minor species, dimensionless stagnation temperature and combustion efficiency along the combustor length are presented and discussed. Further, dimensionless wall static pressure is compared with experimental data reported in the literature. Results show that the reduced chemistry predicts the overall combustion parameters reasonably well. The heat release is predicted to be lower than that of detailed chemistry model. Also, the flow separation due to heat release is predicted to be shorter with the reduced mechanism. In this work, the difference in predictions of supersonic combustion of hydrogen with different chemistry models are discussed.