Submicronic (Mg1-xFex)O (0.05 less than or equal to x less than or equal to 0.40) powders were synthesized by thermal decomposition of oxalic precursors and further calcination under N-2/H-2/H2O 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 (Mg1-xFex)O is studied by SEM, XRD and Mossbauer spectroscopy.