We report on the synthesis of nanostructured Ag4O4 by thermal evaporation of silver films followed by oxidation with beams of oxygen ions with different kinetic energy in the 50-300eV range. This method, which combines simplicity and versatility, allows to control the oxide structural properties, and in particular to obtain Ag4O4 thin films characterized by different nanoscale morphologies and crystalline structure, depending on the pristine silver layer morphology and on the energy of the oxygen ions. Monoclinic and tetragonal Ag4O4 phases, or a mixture of the two, can be obtained. The nanoscale porosity of the material makes it interesting for applications where surface mediated Ag ion release plays a crucial role. (c) 2012 Elsevier B.V. All rights reserved.