<p>The kinetics of the reaction between tungstate ion and hydrogen peroxide in aqueous medium containing phosphate ions, both in the absence and presence of oxidizable organic substrates (alcohols, polyalcohols and carbohydrates), has been followed spectrophotometrically in the ultraviolet range of the electromagnetic spectrum, following at 225&#xa0;nm the decay of the limiting reactant (tungstate ion). The reaction showed a deceleration much more accused than expected for a pseudo-first order process. Two different experimental rate constants (<i>k</i>₁ and <i>k</i>₂) have been determined from each kinetic run, <i>k</i>₁ being consistently higher than <i>k</i>₂. The dependence of <i>k</i>₁ on the hydrogen peroxide initial concentration suggested that the main oxidizing agent was a diperoxo tungsten(VI) complex. For the oxidation of alcohols/polyalcohols both rate constants increased with the number of OH groups. In the case of carbohydrates, the monosaccharides were more readily oxidized than sucrose (a disaccharide). Copper(II) ion (an efficient superoxide radical scavenger) strongly catalyzed the reduction of W(VI), whereas the surface of the spectrophotometric cell walls did not affect appreciably the reaction rate. Acrylamide showed a slight inhibiting effect on the rate, but it did not suffer any chemical change itself at the end of the reaction. In the absence of organic compounds, the activation energy associated with <i>k</i>₂ (65 ± 4&#xa0;kJ&#xa0;mol⁻¹) was considerably higher than that of <i>k</i>₁ (29 ± 2&#xa0;kJ&#xa0;mol⁻¹). Finally, a mechanism coherent with the available experimental information, involving three different oxidation states of tungsten (VI, V and IV) and three inorganic free radicals (hydroperoxyl, superoxide ion and hydroxyl), has been proposed, the strong deceleration of the reaction being explained by the accumulation in the solution of a long-lived intermediate, W(V), that could be partially reoxidized to W(VI).</p> Graphical abstract <p></p>