A challenge in the development of powder based materials is to limit the oxygen contents. In the present work reduction of oxygen/oxides in a duplex stainless steel powder was studied. The main mechanisms ruling the reduction of oxygen in a hydrogen atmosphere have been established. A combination of experiments and mathematical modelling was used. Experiments were performed on small samples of powder, as well as powder encapsulated in a 200x200 mm canister. FEM calculations of the heat transfer in the canister, combined with thermodynamic calculations of the stability, and heat of reduction of oxides were used for the modelling. The experimental features: oxide reduction, heat transfer, and hydrogen transport, are reproduced by the calculations. A high-oxygen powder was used for the experiments, and the oxygen content was reduced from 200 ppm O in the powder, to less than 100 ppm O in the compacted material. The results from the modelling could conclude that this was due to a reduction of Fe-oxides at low temperatures, and Cr-oxides at high temperatures.