The hydrated electron (e(aq)(-)) and hydroxyl radical rate constants with 18 acrylate-, methacrylate-, crotonate-, fumarate- and maleate esters are discussed. The constants approach the diffusion-controlled limit. k(e(aq)(-)) and k(OH) change in opposite direction; if k(e(aq)(-)) is high then k(OH) is small. This tendency is connected with the nucleophilic character of e(aq)(-) and the electrophilic character of OH, although the site of attack of e(aq)(-) and OH is different: carbonyl versus vinyl group.