The leachability and speciation of inorganic trace contaminants of oxy-coal combustion fly ash from a 20 MVVth oxy-pulverized coal combustion (oxy-PCC) demonstration plant have been evaluated. Collected oxy-coal fly ashes show significant differences in their particle size distribution (PSD) and chemical composition as a result of the oxy-fuel combustion operating conditions. While the variation of the PSD in the oxy-coal fly ash can be considered as indicative of the formation of ultrafine particles by the enhanced oxygen concentration, the differences in the chemical composition are attributed to the recirculation of the accumulated CO2-rich flue gas back to the boiler with high impurities of inorganic trace contaminants. Evaluation of the leaching results and the waste acceptance criteria at landfills reveals that all oxy-coal fly ashes (oxy-FAs) can be accepted at nonhazardous waste landfills. However, the leachable concentration of Zn, As, Mo, Cd, and Sb are well above the inert range in the oxy-FAs and that of Cr, Mo, and Se are the upper inert range and close to nonhazardous in some oxy-coal fly ash leachates. Consequently, the potential risk of contaminating the oxy-coal fly ash with excessive amounts of trace contaminants can be very critical to the configuration of an oxy-fuel combustion power plant at full-scale.