Base-catalyzed hydrolysis of coumalic acid (COU) in aqueous-methanol and aqueous-acetone mixtures has been studied kinetically at temperature range from 283 to 313 K. Moreover, the change in the activation energy barrier of COU from water to water–methanol and water–acetone mixtures is estimated from the kinetic data. Solvent effects on reactivity trends have been analyzed into initial and transition state components. These are determined from transfer chemical potentials of the reactants and kinetic data. The transfer chemical potentials δ)mµθ) for COU- anion are derived from solubility data from its calcium, cerium and lanthanum salts. The decrease in rate constant of COU as the proportion of methanol or acetone increases is dominated by transition state (TS). The base hydrolysis reaction of COU follows a rate law with kobs= k2[OH-] and the reaction mechanism is suggested. The high negative values of entropy of activation supports the proposal mechanism, i.e. the investigated reaction takes place via the formation of an intermediate complex. Thus, the ring opening of the intermediate complex would be the rate controlling step.