Аннотация:In microwave spectra of 2-chloro-4, 5-dimethyl-1, 3, 2-dioxaphospholene in the region 7-53 GHz a-type and c-type transitions were assigned for parent molecule and for isotopic species with 37Cl, 13CMe, 13CRing in natural abundance. The rotational constants were determined by least squares fitting of calculated frequencies of rotational transitions to the experimentally obtained data. The experimental values of rotational constants were used to calculate principal moments of inertia and substitution coordinates in the principal axes system of parent molecule.