A one-step, high-yield procedure is reported for the preparation of a 1:1 mixture of the two isomers of 1-chlorophospholene-1-oxide which may be separated by spinning band distillation. The isomerically pure chlorides were hydrolyzed to form the corresponding 1-hydroxyphospholene-1-oxides. These, as well as the precursor chlorides, were characterized by1H and31P nmr, mass spectrometry and IR.