Comparative analysis of the prediction ability of several modern detailed kinetic models describing the ignition and combustion of hydrogen/air mixture in a supersonic flow is conducted. The possible uncertainties in the rate constants of principle reactions responsible for the chain mechanism development in the H2/O2(air) mixture are inspected. Special attention is paid to matching the lengths of ignition and energy release zones and combustion completeness predicted by considered kinetic models in both one-dimensional homogeneous premixed flow and two-dimensional non-premixed flow in a scramjet model combustor. It is demonstrated that, while the difference in the induction zone length predicted by considered kinetic models does not exceed 30%, the discrepancy in the calculated values of energy release zone length may be as large as a factor of 4. As a consequence, different reaction mechanisms give distinguished magnitudes of combustion completeness at the combustor exit.