PURPOSE: To obtain the subject compounds useful as catalysts, intermediates of an agricultural or pharmaceutical agent, etc., in an extremely efficient manner in high yield at a low cost on an industrial scale by oxidizing a specific ethane halide.

CONSTITUTION: A compound of the formula HCF2COX is obtained by oxidizing an ethane halide of the formula HCF2CXClH (X is Cl or F), preferably by photooxidation in the presence of oxygen or by high-temperature oxidation in the presence of oxygen. Further, in the case of photooxldation, a protecting layer consisting of a transparent fluororesin is preferably placed between a light source and a reacting substance to prevent the direct contact of a glass of the light source with the reacting substance. The reaction temperature of the photooxidation is preferably 50 to 150°C for a gas phase reaction and -20 to 70°C for a liquid phase reaction. Further, in the case of high temperature oxidation in the presence of oxygen, the reaction temperature is preferably 200-350°C.