The effect of a high magnetic field of 7 T on styrene polymerization reactions was taken under study. The intervened magnetokinetic modifications are correlated to the system of radical initiation, respectively: benzoyl peroxide, 2, 2'-azobis(2-methylpropionitrile), 4,4'-azobis(4-cyanopentanoic acid), and 1,1'-azobis (cyclohexan-1carbonitrile). The reaction products are also characterized from the viewpoint of their molecular weights correlated with the reaction conditions, as well as their thermal stability. (c) 2005 Wiley Periodicals, Inc.