The present study comprises a kinetic comparison of the reactivity of electrochemically generated superoxide, O 2 - , and hydroperoxyl, HO 2 , radicals toward a mixture of β-carotene geometric isomers versus all-trans-retinol (vitamin A). Rate constants were determined by computer simulation of experimental cyclic voltammetric data. It is reported that all-trans-retinol reacts more readily with both O 2 - and HO 2 than a mixture of geometric β-carotene isomers. Specifically, the latter is unreactive at =<25 mM with O 2 - within the timescale of cyclic voltammetry, while it reacts with HO 2 at least an order of magnitude slower than all-trans-retinol. Our results indicate that all-trans-retinol is a better radical scavenger than a mixture of geometric β-carotene isomers and parallel the results of a recent epidemiological study which has shown that vitamin A may be a better anticarcinogenic agent than β-carotene.