This paper deals with a theoretical and experimental investigation on chemical looping gasification of biomass. The process was conceived by combining in a fluidized bed CO2 gasification and oxygen delivery from a suitable oxygen carrier in order to increase the carbon conversion to CO. In such a way no dilution in nitrogen occurs and exceeding carbon dioxide can be further separated, e.g. by membrane. The results of the theoretical insights based on Cu oxide as O2 carrier show that producer gas with heating value higher than 8 MJ/m3 can be obtained at 900°C and equivalence ratio of 0.5. First experimental results in batch fluidized bed gasifier proved the effectiveness of a purposely developed oxygen carrier and its contribution (up to two times) in increasing the CO yield during the first stage of gasification.