The adsorption of oxytetracycline from aqueous solution by the resin Amberlite IR 120 was studied. The effect of different experimental parameters such as contact time, initial concentration of OTC 40–200 mg/l, initial pH 2–12 of aqueous solution, adsorbent dose 0.5–3 g/l, and stirring speed 100–700 rpm on the adsorption of OTC were investigated. The kinetic adsorption experimental results were analyzed using pseudo-first order, pseudo-second order and Elovich kinetic models. The adsorption process was found to follow a pseudo-second order kinetic model and the corresponding rate constants were obtained. A film-pore diffusion (FPD) mass transfer model has been developed to predict the concentration distribution in the fluid phase, based on the external mass transfer coefficient and the effective diffusion coefficient. The values of the external mass transfer coefficient (βL) and effective diffusion coefficient (Deff) were found to decrease with increasing OTC concentration. The comparison between the experimental and the theoretical curves allowed us to note that the film-pore diffusion mass transfer model gave a good agreement with the experimental data for all the values of initial OTC concentration.