The catalytic ignition of a mixture of methane and air in a planar stagnation-point flow over a platinum foil is studied The heterogeneous reaction mechanism is modeled with twelve heterogeneous reactions, including the adsorption processes of both reactants, the desorption kinetics of reactants and main products, and a ser of surface reactions of the Hinshelwood-Langmuir type. The critical conditions for the catalytic ignition are found using high activation energy asymptotics of the desorption kinetics of the adsorbed reactant O(s). The analytical results are compared with published experimental data. The agreement is good at least qualitatively.