Nanocrystalline Fe and Co materials can be prepared in the form of ultrafine powders by the gas phase condensation method. By storage of the passivated nanocrystalline materials in raw vacuum, the samples can be maintained for long periods without altering their degree of oxidation. In the case of iron, the oxidation proceed in two steps of different oxidation rate while the cobalt oxidation proceed with a continuous decrease in the oxidation rate. In the early stages of passivation, the oxide overlayer is so thin that the MOx-M interface affects the electron photoemission behaviour of the oxide layer, so that an increase in the relaxation energy of the photohole is observed as compared to that of bulk oxides.