A cw CO2laser is used to vibrationally excite CH2D2. IntentionalVTdeactivation competes with interisotopeVVtransfer and prepares a sample of gas in which the CH2D2is excited while the CH4remains unexcited on a steady‐state basis. Subsequent reaction of this mixture with chlorine atoms and molecules forms a stable product, deuterated methyl chloride, enriched in deuterium by up to 72%. Extension to the CH3D system will be discussed. A conservative estimate of the energy requirement for a commercial facility (natural abundance feed) based on the latter system gives a value within a factor of 4 of that required by the currently used H2O/H2S commercial process.