Adsorption equilibria Of glutaric acid and glyoxylic acid on a weakly basic ion-exchanger which has a tertiary amine functional group were investigated experimentally and theoretically in this study. Amberlite IRA-67 was used as the ion-exchange resin. The time to reach an equilibrium state, effects of amount of adsorbent, temperature, and initial acid concentrations on adsorption efficiency and distribution coefficient of acid adsorption were investigated, experimentally. The Langmuir, Freundlich, and Temkin adsorption isotherms were calculated. The equilibrium isotherms were significantly dependent on initial acid concentration. The Langmuir isotherm was found to best represent the data for both acids. The adsorption of both acids followed pseudosecond-order kinetics. Diffusion is not the only rate-controlling step.