This book presents data on the optical constants of metal elements (Na, Au, Mg, Hg, Sc, Al, Ti, 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, 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 (E)=1(E)+2(E), the complex refractive index n*(E)=n(E)+ik(E), the absorption coefficient (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.