Irradiation with high energy heavy ion beams has been investigated as a technique for improving the quality of highly reflecting metallic surfaces to be used as laser mirrors. Properties such as reflectivity, corrosion resistance, film bonding, and threshold to laser surface damage have been examined. Modifications of composition and microstructure of the material associated with the heavy ion irradiation have been measured with RBS, TEM, SEM, Auger, and ESCA. Reflectivity and extinction coefficient measurements were made using ellipsometry techniques. Observations indicate that keV heavy ion irradiations in the fluence range of 1015 to 1016 cm−2 produce significant surface smoothing. Additionally, MeV implants of heavy ions into films of Cu, Ag, Au and Al deposited on molybdenum substrates resulted in improvements to both tarnish resistance and structural bonding integrity.