Publisher Summary This chapter analyzes activated carbons obtained from agricultural byproducts (olive stones, H carbons, almond shells, and C carbons) in relation to their possible application as eliminator of pollutants. Porous carbon materials usually contain polymodal distribution of pores, the sizes of which vary from molecular dimension to several hundred nanometers. They can be tailored with high capacity of adsorption for a particular adsorbate by an appropriate selection of raw materials, preparation process, and specific treatments. Some of the activated carbons used as adsorbents were obtained by carbonization and simultaneous activation—in a flow of CO2—of almond shells and olive stones at 1,123 K and for different time periods ranging from 2–30 hours. In the adsorption process, the specific interactions depend on the chemical functionalities of the molecules to be adsorbed. The introduction of chemical groups on the surface of the adsorbents also plays important role in the adsorption process because of electrostatic or chemical interactions.