Extensive optimization on the fabrication of Mo/Si multilayer systems is carried out at the FOM Institute Rijnhuizen using e-beam evaporation. The process is being optimized including parameters such as variation of the mirror's center wavelength, the metal fraction, deposition parameters, and the layer composition. Reflectivities of 69.5% are demonstrated at normal incidence, with values of 67 to 69% being routinely achieved, demonstrating the capabilities of the deposition process. Some evidence of smoothening to interface roughness values lower than the roughness of the initial substrate is given. Furthermore, investigation of the temporal behavior of the coatings does not indicate any loss of reflectivity over an eight-month period. An analysis of the multilayer composition and the interface roughness is given. The reflectivity measurements have been carried out at the PTB facilities at the electron storage rings BESSY I and BESSY II in Berlin. The results of measurements at both facilities are found to be identical and accuracy is discussed in detail.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.