Abstract: The general formulations of the chemically reacting surface boundary condi-tions for non-equilibrium boundary layer chemistry are derived from the theoretical analysisand their specific cases are investigated. When the ablation surface is fully catalystic to allgas phase reactions adjacent to it,the transfer coefficient approach is used to simplify thecalculations by decoupling the ablating surface procedure from a non equilibrium bound-ary layer procedure and a general method for computing the ablation su...