We study the introduction of Zr as a third material within a nanometric periodic Mg/Co structure designed to work as optical component in the EUV range. Mg/Co, Mg/Zr/Co, Mg/Co/Zr and Mg/Zr/Co/Zr multilayers are designed, then characterized in terms of structural quality and optical performances through X-ray and EUV reflectometry measurements respectively. For the Mg/Co/Zr structure, the reflectance value is reported to be 50% at 25.1 nm and 45° of grazing incidence. Nuclear Magnetic Resonance (NMR) measurements are performed to study the nearest neighbour local environment around the Co atoms.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.