Starting from any detailed reaction model, an automatic reduction procedure based on quasi steady-state approximation for selected chemical species and on elimination of the fast reactions has been developed. The reduced reaction models developed on the basis of ignition delay of a fuel-air mixture in a zero-dimensional configuration and laminar flame configurations are then extended to simulations of supersonic reacting shear layers. Predictions of a hydrogen-air shear layer obtained with a detailed kinetic model and reduced reaction models developed are presented indicating good quantitative agreement at various cross sections in the two-dimensional flow field considered. Further analysis also shows that the models can adequately explain basic combustion characteristics associated with the location of detached reaction fronts and ignition delay of zero-dimensional configuration. The present simulations are also being extended to shear flows comprising of ethylene-air system, including vitiation effects.