Lanthanum is a chemical element with the symbol La and atomic number 57. Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is a lanthanoid. It is found in some rare-earth minerals, usually in combination with cerium and other rare earth elements. Lanthanum compounds have numerous applications such as catalyst, additives in glass, carbon lighting for studio lighting and projection, ignition element in lighters and torches, electron cathode, scintillator, and others. This book reviews research on the biomedical applications of lanthanum, the effect of lanthanum in heterogeneous catalysts, lanthanum strontium manganites for application as cathodes in solid oxide fuel cells, and others.