Fluidized bed combustors generally exhibit good mixing characteristics, but there can be localized regions where there is insufficient oxygen to fully combust the fuel. Through incorporation of an oxygen carrier into a high pressure, pulverized fuel based oxy-fluidized bed combustor it should be possible to reduce or eliminate regions with insufficient oxygen present to complete combustion. In this paper we investigate the use of a Canadian ilmenite ore based oxygen carrier to enhance combustion performance and sulfur capture for atmospheric and pressurized oxy-FBC systems. The paper includes a description of potential pressurized system configurations with a discussion of related benefits and potential challenges. CanmetENERGY's 50 kW(th) pilot scale atmospheric pressure oxy-fluidized bed combustor (oxy-FBC) was used to demonstrate the concept of oxygen carrier assisted combustion using two Canadian coals with under bed fuel and sorbent injection. The CO emissions were significantly reduced by replacing the inert bed material with the oxygen carrier (ilmenite ore); with CO concentrations in the flue gas reduced up to 30 vol % and 13 vol % when burning Highvale coal and Poplar River coal, respectively. The improvement in combustion was even more pronounced in the bed region, in particular, under conditions of low excess oxygen and/or low bed temperature. Analysis of solid samples (XRD) and flue gas condensates (acidity) has provided further evidence of the oxygen carrier improving combustion performance and reducing the risk of bed agglomeration.