The polar epoxides, glycidonitrile, dimethyl glycidonitrile, tetracyanoethylene oxide, epicyanohydrin, 4,4,4‐trichlorobutylene‐1,2‐epoxide, and 1,1‐dichloro‐3,4‐epoxy‐1‐butene were prepared, characterized by their infrared and nuclear magnetic resonance spectra and their polymerizations studied. Epicyanophydrin was found to be an unpolymerizable dimer, and those epoxides with a cyano group attached directly to the epoxide ring could not be polymerized. The halogenated epoxides, 4,4,4‐trichlorobutylene‐1,2‐epoxide and its dehydrochlorination product, 1,1‐dichloro‐3,4‐epoxy‐1‐butene were polymerized to high polymers with a complex catalyst from aluminum alkyl, acetyl acetone, and water. The polymerization of these monomers gave low conversions and required large amounts of catalyst. Higher conversions were obtained by copolymerization with propylene oxide or terpolymerization with propylene oxide and allyl glycidyl ether. The polymerizability of the substituted epoxide in (where X is CH3, ClCH2, Cl3CCH2, and Cl2CCH) was found to follow the order: CH3 > ClCH2 > Cl3CCH2 > Cl2CCH. The polymers of 4,4,4‐trichlorobutylene‐1,2‐epoxide and its dehydrochlorination products were not vulcanizable through the chlorine functionality or the olefinic unsaturation of the type Cl2CCH. The presence of an active third monomer such as allyl glycidyl ether was necessary to facilitate vulcanization. Properties of such vulcanizates are reported.