The reaction of chlorodifluoromethane (R-22) with sodium methoxide produces difluoromethoxymethane, an alternative refrigerant with low ozone depleting potential. In this study a kinetic model of the dehydrochlorination process was identified, based on rate data obtained from a semi-batch gas–liquid reactor. The reaction was studied at a reaction temperature of 283–303K, R-22 inlet partial pressures of 40.5–60.8kPa and initial sodium methoxide concentrations between 1.5 and 2.5mol·dm−3. The products obtained were difluoromethoxymethane and trimethyl orthoformate as well as sodium chloride and fluoride salts. The reaction proceeds via a three step mechanism, initiated by an α-elimination and involving a difluoromethylene intermediate. The elimination step has an identified pre-exponential factor of 1.18 × 104dm3·mol−1·min−1 and activation energy of 15.54kJ·mol−1. The reaction yielding the target compound has a pre-exponential factor of 1.15 × 108dm3·mol−1·min−1 and activation energy of 47.67kJ·mol−1. The byproduct formation reaction has a pre-exponential factor of 8.25 × 101(dm3·mol−1)2·min−1 and activation energy of 12.75kJ·mol−1. In a semi-batch system the reaction is strongly inhibited by the formation and accumulation of precipitated sodium salts. This feature was incorporated into the reaction model using an inhibition term.