The feasibility of the reuse of petroleum coke, withof high sulphur content, produced as waste in a Mexican petroleum refinery, its properties for use in water treatment was were assessed. Several classical activation methods were used and the physicochemical characteristics of the treated material were measured using normal ASTM standards. Use of scanning electron microscopy and microprobe analysis permitted most of the effects of the activation processes on the structure and properties of the coke. Adsorption capacities of mercury and silver and physicochemical characteristics determined for these activated carbons as well as scanning electron microscopy show that the H3PO4 is the best activating agent. It is shown that the process is highly promising for the production of an activated carbon aimed at the removal of heavy metals from wastewater.