The electron spin resonance spectra of radicals which are formed during the oxidation, by the Ti(III)–hydrogen peroxide system, of mesoinositol, D-glucose, D-galactose, D-fructose, D-ribose, and L-arabinose are described. It is shown that the radicals which are derived from these compounds by the abstraction of a hydrogen atom from the C–H bond of a CH(OH) fragment undergo acid-catalysed elimination of water to give carbonyl-conjugated radicals.