AbstractPhoto and thermal polyrecombinations of some captodative substituted cyano‐, methoxycar‐bonyl‐, and phenylmethane derivatives were carried out using peroxides as oxidizing agents at room temperature and 130°C. Cyano‐substituted methane derivatives easily gave a polymer with a molecular weight of several thousands by both photo and thermal polyrecombinations. Especially, phenylacetonitrile afforded a polymer in good yield even under conditions at which diphenylmethane gave no polymer. Methyl methoxyacetate gave no polymer in the thermal reaction, but afforded a polymer when using high concentrations of an oxidizing agent in the photoreaction.1H nuclear magnetic resonance and electron paramagnetic resonance spectra demonstrated the production of a polymer with a structure mainly consisting of 1,1‐disubstituted methylene units and the generation of a captodative substituted methyl radical in the react