Radical polymerization of butyl acrylate (BA) and random copolymerizations of styrene (St) and BA and St and methyl methacrylate (MMA) in the presence of 7-aza-15-hydroxydispiro[5.1.5.3]hexadecane-7-yloxyl (1) and 1-aza-2,2-dimethyl-4-hydroxyspiro[5.6]dodecane-1-yloxyl (2) were carried out. Radical polymerization of BA at 120 T in the presence of 1 gave poly(BA) with M-n = 20200 and M-w/M-n = 1.30 at 23% conversion. The termination of polymerization observed around similar to20% conversion was solved to a certain extent by an addition of small amounts of dicumyl peroxide, and poly(BA) with M-n = 37400 and M-w/M-n = 1.33 was obtained in 46% yield. Random copolymerizations of St and BA and St and MMA in the presence of 1 and 2 at 80 T gave the corresponding random copolymers with narrow polydispersities of 1.12-1.38 at the molar fraction above 0.30 of St in feed. The kinetic study for the NO-C bond homolysis of the corresponding alkoxyamines prepared from 1 and 2 were carried out, and evaluation of the preexponential factors (A(act)) and the activation parameters (E-act) showed that the steric factors of the nitroxides are reflected mainly on E-act. (C) 2003 Elsevier Science Ltd. All rights reserved.