This book presents data on the optical constants of metal elements (Na Au Mg Hg Sc Al Ti β-Sn V Cr Mn Fe La Th etc.) semimetal elements (graphite Sb etc.) metallic compounds (TiN VC TiSi2 CoSi2 etc.) and high-temperature superconducting materials (YBa2Cu3O7-δ MgB2 etc.). A complete set of the optical constants are presented in tabular and graphical forms over the entire photon-energy range. They are: the complex dielectric constant ε(E)=ε1(E)+iε2(E) the complex refractive index n*(E)=n(E)+ik(E) the absorption coefficient α(E) and the normal-incidence reflectivity R(E). The book will aid many who are interested to know the optical constants of the metals semimetals metallic compounds and high-temperature superconducting materials in the course of their work.