ignocellulosic agricultural wastes e.g. corn cobs, straws and corn stalks were converted into carbonaceous adsorbents using a sequence of thermal and chemical activation processes. The derived solids obtained after each type of activation were characterized by determination of fix carbon content, iodine number, Boehm titration and DRIFT spectrometry. The results obtained at the adsorption tests were well correlated to those of the characterization, showing that the most promising adsorbents for amoxicillin removal were those submitted to a thermal treatment followed by a chemical alkaline activation, followed by washing and a secondary thermal treatment. The most promising bio-based adsorbent was the one derived from corn stalks (90.6% adsorption efficiency).