In this book, the authors present current research in the study of the chemical properties, applications and environmental effects of niobium. Topics discussed include the structure and properties of Nb under severe plastic deformation and in high-strength Cu-Nb nanocomposites; the crystal structure of ordered carbide phases and revised sequence of phase transformations associated with the ordering of strongly nonstoichiometric cardides of group V transition metals; niobium-based alloys as hydrogen permeable membrane for hydrogen separation and purification; and electrode processes in anodic oxide films of niobium.