The conversions into hydrocarbons of methanol, dimethyl ether and chloromethane (MTH, DTH and CTH, respectively) on a H‐ZSM‐5 zeolite catalyst were compared trough ab‐initio calculations and experiments, using a fixed‐bed reactor and in‐situ FTIR spectroscopy. The molecular modelling of the reaction was performed using force field calculations. The nature and location of retained species were assessed by a combination of techniques. The experimental results of activity, product distribution and deactivation match these of the molecular modelling as the three reactions proceed through the dual‐cycle mechanism. However, the initiation, evolution and degradation of hydrocarbon pool species are kinetically different depending on the reactant. The reactions are faster in the order DTH>MTH≫CTH whereas the rate at which coke forms and grows (linked with the rate of deactivation) is in the order CTH≫DTH>MTH.