Oxygen carrier aided combustion (OCAC) emerges as a promising solution for the combustion of biomass and waste, such as swine manure, which is produced in large quantities in Spain. OCAC technology is based on the use of fluidized bed reactors for the combustion of solid fuels using an oxygen carrier as bed material. In a fluidized bed reactor there are oxidizing and reducing zones. In OCAC, the aim is to have more homogeneous combustion throughout the boiler by reducing and oxidizing the oxygen carrier in the reducing and oxidizing regions of the reactor. The active bed material is reduced in the fuel-rich parts of the combustion chamber, providing the necessary oxygen where it is scarce in the gas phase mainly by reaction with pyrolysis and gasification products such as CO and H2. In contrast, the oxygen carrier is oxidized in oxygen-rich areas. The objective of this study is to evaluate the effects of temperature and excess oxygen on the combustion efficiency and also on the fate of nitrogenous compounds, including N2, NH3 and NOx. In this work, experimental tests have been carried out in a 3kWth Oxygen Carrier Assisted Combustion (OCAC) unit using swine manure as fuel and different mineral oxygen carriers based on iron (Tierga, ilmenite) and manganese (Gabon). High combustion efficiencies (87-98%) were achieved. Among all oxygen carriers used, Gabon ore and ilmenite exhibited the best performance. Additionally, it was observed that the predominant conversion of nitrogen from swine manure was mainly to NO and N2.