2-Thiocyanatoethyl vinyl ether (TCEVE), a vinyl ether, was observed to be polymerized in moderate yields with radical initiators such as dimethyl 2,2'-azobisisobutyrate (MAIB) and 2,2'-azobisisobutyronitrile. The rate (R-p) of polymerization of TCEVE with MAIB in benzene st 60 degrees C was given by R-p = k[MAIB](0.8)[TCEVE](1.0). The overall activation energy of the polymerization was 105 kJ/mol. The number-average molecular weight ((M) over bar(n)) of the resulting poly(TCEVE) was in the range of 1700-3600, corresponding to polymerization degrees of 13-27. (M) over bar(n) tended to decrease with increasing TCEVE concentration, suggesting chain transfer to the monomer. The IR, H-1-, and C-13-NMR spectra and the thermal degradation behavior of the radically formed poly(TCEVE) distinguishably differed from those of a cationically formed polymer and indicated that the radical polymerization of TCEVE: propagates with transfer of the cyano group. Radical copolymerizations of TCEVE with some vinyl monomers were examined on the monomer reactivity ratios and structures of copolymers.