The adsorption equilibria of propionic acid and glyoxylic acid on alumina are investigated experimentally and theoretically in this study. Alumina was used as the adsorbent. The period of achieving the equilibrium state and the effects of the amount of adsorbent, temperature, and initial acid concentration were investigated experimentally. Langmuir, Freundlich, and Temkin adsorption isotherm equations are fitted well with the experimentally measured data. It was found that the equilibrium isotherms depended on the initial acid concentration significantly. The Langmuir isotherm was found to best represent the data for both of the acids. The pseudosecond-order model, intraparticle diffusion model, and Elovich model were applied to experimental data. The adsorption of both acids followed pseudosecond-order kinetics. Diffusion is not the only rate-controlling step.