This paper reports the preparation and characterization of carbonaceous materials obtained from three types of vegetable wastes provided by agricultural industries. Soft carbonization (280 ºC) and H3PO4-activation procedures were used to convert the agricultural wastes to carbon powders with high adsorbent capacity, being this process an excellent via to eliminate and exploit the huge mass (a lot of tons) of vegetable residues remained after each harvest every year in several Colombian agro-industries. The powders were characterized by X-ray diffraction (XRD), IR spectroscopy, scanning electron microscopy (SEM) and N2-adsorption isotherms. XRD and IR verified the formation of carbons, and SEM showed small particles (20 to 500 ¿m) with characteristic morphology for each type of residue used and abundant cavities of different sizes. N2-adsorption analyses showed that these carbons have high adsorption capacity with important surface area values and large pore volumes. These results indicate that these powders can be used as potential adsorbents for different gaseous or liquid pollutants.