The labelled compound was prepared by chlorination of [2-14C]acetone obtained from the barium salt of [1-14C]acetic acid by pyrolysis. The reaction product 1,1-dichloro [2-14C]acetone was converted to 2-dichloromethyl-2-methyl [2-14C]-1,3-dioxolane by condensation with ethylene glycol in the presence of thionyl chloride. Radiochemical yield: 62% based on [1-14C]acetic acid.