In this work presented are the results of application of Coherent Anti-Stokes Raman Scattering (CARS) to the measurements of gas parameters in a pulsed combustion chamber specially designed for modeling of hydrogen- and hydrocarbon-oxygen combustion at high temperature (∼3500 K) and pressure (∼20 MPa). Besides temperature, pressure, and species relative concentration measurements together with temporal behavior, methodical aspects of CARS spectroscopy as a diagnostic tool were investigated from the point of view of proper choice of a probe molecule. Spectra evolution of selected probe molecules with pressure and temperature were analyzed.