Sorbic alcohol (CH3CH=CHCH=CHCH2OH) and 2-phenylethanol (C6H5CHCH2OH) or phenylacetic acid/ phenylacetate (C6H5CH2COOH/C6H5CH2COO-) have been studied as a model for the conjugated double bond (C-C=C-C=C-C-NH-) and phenyl (C6H5-C-C-O-) residues in 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-dienoic acid. The latter is known to play a key role in the toxicity of microcystins, which are well-known natural toxins found in water. Particular attention was focused on studying the products of the ionizing radiation-induced organic peroxyl radical intermediates in the separated systems compared to those obtained in the mixed solutions of sorbic alcohol and the aromatic compounds. The aromatic hydroxylation and peroxide yields reflect the respective reaction rate constants of the above solutes with (OH)-O-. radicals at pH 7.0. In contrast, at pH 3.1 the effect of sorbic alcohol on decreasing the aromatic hydroxylation and increasing the peroxide yields is considerably higher than expected on the basis of (OH)-O-. scavenging only. The results are discussed in terms of scrambled reactions between the peroxyl radicals in light of the lack of observed products arising from phenyl hydroxylation in the photocatalytic destruction of microcystin.