Abstract: A process for producing vinyl polymers involving polymerization of vinyl monomers in the presence of polyarylenealkylenes of the formula: ##STR1## WHEREIN Ar.sub.1 and Ar.sub.2 are ##STR2## m + n + 2 to 30, k = 1 or 2, at k = 1 Ar.sub.1 and Ar.sub.2 are also ##STR3## where X is H, a C.sub.1 -C.sub.4 alkyl, or in the presence of hydroperoxides of said polyarylenealkylenes; said polyarylenealkylenes or hydroperoxides thereof are used in an amount ranging from 0.01 to 15% by weight of the starting vinyl monomers. The process of the present invention makes it possible to obtain vinyl polymers featuring an enhanced heat-resistance and, in some cases, improved mechanical and electrical properties.