Submicronic (Mg 1 - x Fe x )O (0.05 ≤ x ≤ 0.40) powders were synthesized by thermal decomposition of oxalic precursors and further calcination under N 2 /H 2 /H 2 O atmosphere. The precursors are stoichiometric up to 10 at.% Fe; otherwise, mixtures of oxalates are obtained. The influence of the iron content on the morphology and microstructure of (Mg 1 - x Fe x )O is studied by SEM, XRD and Mossbauer spectroscopy.