Sub micrometer hollow metallic spheres of Ni-P alloy were produced in aqueous solutions at 80 degrees C by chemical reduction over vesicle templates formed by self-assembling of sodium dodecyl sulfate (SDS) amphiphilic molecules. By varying the pH and SDS concentration (maintaining carefully fixed all other parameters) we obtain different sizes and size distributions, in a monomodal or sometimes bimodal regime. The higher the bath pH the lower the sphere sizes. The sphere shells are nanostructured and the higher the phosphorus content the lower the crystallite sizes. Mass density was of only 3.8 g/cm(3) as a consequence of the hollow morphology and nanostructure. These sphere shells are promising candidates for hydrodesulphurization catalyst due to their high specific area and chemical resistance to sulfur. Characterization was made by XRD, SEM, EDX and thermal analysis.