The first CO2laser enrichment of deuterium in the gaseous phase of formaldehyde is reported. Irradition with pulses from a ∼20‐MW CO2TEA laser focused strongly onto the sample yields highly efficient selective photodissociation of the formaldehyde molecule. A deuterium enrichment factor of approximately 40 is found for formaldehyde gas at an initial pressure of 20 Torr, after irradiation with 300 laser pulses.