The induction zone characteristics of a planar subsonic high‐speed reactive flow downstream of a specific origin are investigated theoretically for the global irreversible reactionF+Ox→&ngr;P. The equation of state for the reacting gas mixture is more general than that for a constant molecular weight gas. Perturbation methods based on the limit of high activation energy are used to construct the general parameter‐dependent analytical solutions. The dependence of the ignition delay distance on the kinetic, stoichiometric, and flow parameters is discussed in detail. Significantly, it is shown that the reaction with a mole decrement (&ngr;=1) yields the minimum, and a mole increment (&ngr;=3) yields the maximum ignition delay distance when the chemical heat addition and the origin values of parameters are fixed. The physics and length scales found from the perturbation analysis are used as a guide in generating supporting numerical solutions.