Technical Abstract: Fast pyrolysis is rapid heating in the absence of oxygen resulting in decomposition of organic material. When applied to biomass, it produces bio-oil, bio-char and gas. The Agricultural Research Service (ARS) of the USDA has studied fluidized-bed fast pyrolysis of several bimoass including perennial energy crops, plant and animal wastes for bio-energy production. Owing to the short residence time in the fluidized-bed pyrolyzer, required for maximizing bio-oil production, the bio-char structure tend to be underdeveloped thereby impacting its full potential application as a value-added coproduct. In this study, we investigate ex-situ steam activation as one upgrading technology for adding value to the said fast-pyrolysis bio-chars. The as-produced bio-chars of several substrates from the fluidized-bed pyrolyzer and their respective steam-activated counterparts were characterized for their surface areas and adsorption of a suite of metal ions (copper, cadmium, nickel and zinc). Surface areas increased with activation from around zero up to 837 m2/g with concomitant pore development evidenced by scanning electron microscopy. Affinity to Cu2+ was highest with adsorption efficiencies for 1mM solutions ranging from 60 to 85%. Metal ion adsorption was feedstock dependent and increased with activation possibly due to improved access to highly reactive adsorption sites associated with the inorganic material present in the feedstock. Because of their higher yields and metal ion uptake, broiler litter and alfalfa stems appear to be the feedstock of choice when considering fast pyrolysis bio-char for metal ion uptake. However, if the development of large surface areas is required, guayule bagasse and soybean straw could be the preferred feedstock. Ultimately the fine balance relies on the ability to produce a good quality bio-oil as fuel and a usable bio-char and/or activated char from low value agriculture waste materials.