Chemical ionization of n-hexane, methane, and acetylene is experimentally studied behind reflected shock waves over a wide temperature range at nearly atmospheric pressure and simulated within the framework of the unified kinetic mechanism developed in the present work. The dependences of the concentration of free electrons measured with a microwave interferometer and an electric probe on the temperature and mixture composition are reported. The experimental data and the results of kinetic simulations are demonstrated to be in close qualitative and quantitative agreement.