Enrichment of the carbon isotopes by photodissociation or photochemical reaction of Freon (CF2Cl2) induced by a TEA‐CO2laser has been reported recently by several authors. The present work shows that large effects on the chlorine isotopes are also induced. Their laser‐wavelength dependence has been measured, and some complementary information on the carbon isotopic effects has been collected. Excitation around 930 cm−1yields an enrichment in37Cl in the residual CF2Cl2, and excitation around 1085 cm−1has an opposite effect, while13C enrichment is found around both 1090 and 922 cm−1and12C enrichment is found around 1065 cm−1. These effects can be qualitatively explained with the known fundamental vibrations &ngr;1(922 cm−1, stretching mode) and &ngr;6(992 cm−1, rocking mode) of CF2Cl2. The efficiency of the photodissociations of CF2Cl2induced by a CO2laser is evaluated, and an effective threshold energy density of 3 J/cm2is found at 1089 cm−1.