Reactions of alpha-hydroxyalkyl radicals with 3,5-pyridinedicarboxylic acid (3,5-PDCA) and nicotinic acid (NA) were studied at appropriate pHs in aqueous solutions by pulse radiolysis technique. At pH 1, CH3C center dot HOH and center dot CH2OH radicals were found to react with 3,5-PDCA by rate constants of 2.2 x 10(9) and 5.1 x 10(8) dm(3) mol(-1) s(-1), respectively, giving radical adduct species. The adduct species formed in the reaction of (CH3CHOH)-H-center dot radicals with 3,5-PDCA underwent unimolecular decay (k = 9.8 x 10(4) s(-1)) giving pyridinyl radicals. Reaction of (CH3)(2)(COH)-O-center dot, (CH3CHOH)-H-center dot, and (CH2OH)-C-center dot radicals with NA at pH 3.3 gave the adduct species which subsequently decayed to the pyridinyl radicals. At pH 1, wherein NA is present in the protonated form, (CH3)(2)(COH)-O-center dot radicals directly transfer electrons to NA, whereas (CH3CHOH)-H-center dot and center dot CH2OH radicals react with higher rate constants compared with those at pH 3.3, initally giving the adduct species which subsequently undergo elimination reaction giving pyridinyl radicals. Reactions of a-hydroxyalkyl radicals with 3,5-pyridinedicarboxylic acid and nicotinic acid are found to proceed by an addition -elimination pathway that provides one of the few examples of organic inner sphere electron -transfer reactions. Rate constant for the addition reaction as well as rate of elimination varies with the reduction potential of alpha-hydroxyalkyl radicals.