The identity and rate constants of elementary steps in primary reactions of oxidative coupling of methane (OCM) over Pb2+ and/or F- substituted hydroxyapatite (HAP, Pb-HAP, HAP-F, and Pb-HAP-F) catalysts have been studied. The rigorous kinetics analysis suggests that HAP and HAP-F initiated the reaction between adsorbed methane and O-2 following Langmuir-Hinshelwood behavior. The Pb-HAP and Pb-HAP-F, however, enabled the reaction between gaseous methane and adsorbed O-2 in the Eley-Rideal mechanism. The F- substitution of OH- weakened both O-2 adsorption and C-H bond activation, leading to low methane conversion and slightly higher C2H6 selectivity. The substitution of Ca2+ by Pb2+ weakened both methane and oxygen adsorptions, but maintained C-H bond activation and raised C2H6 selectivity. The present analysis explored for the first time the effects of cation and/or anion in HAP on OCM reactions in which the analysis has been detailed and quantified in the nature of the mechanism-based kinetic models. (C) 2016 Elsevier Ltd. All rights reserved.