Cobalt(II) bound to copolymer of maleic acid and ethyl vinyl ether, crosslinked with 10 mol% 1,6-hexamethylenediamine was found to catalyze the oxidation of 2-styryl-1,3-dioxane and its alkyl substituted derivatives as well as 4,5-dimethyl-2-styry1-1,3-dioxolane affording hydroxy-alkyl-cinnamates. The effect of polymeric Co(II) complex on the regioselectivity of the oxidation of 4-methyl-2-styryl-1,3-dioxane and cis-syn 4,5-dimethyl-2-styry1-1,3-dioxolane was observed. A free-radical mechanism is proposed.