Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight. It is found in a number of minerals, the most important being monazite and bastnasite. Commercial applications of cerium include catalysts, additives to fuel to reduce emissions and to glass and enamels to change their colour. In this book, the authors study the molecular structure, technological applications and health effects of cerium. Topics include the synthetic and structural features of ceriopolyoxotungstates; cerium-based corrosion inhibitors; tetravalent cerium chemistry; comparative toxicity of cerium and other rare earth elements (REEs) in plant and invertebrate test systems; cerium-based catalysts for the selective catalytic reduction of NOx with NH3; cerium oxide and its reduction in composite materials under hydrogen containing atmosphere; cerium as fertiliser for soils in Russia; and the structure and reactivity of cerium IV complexes with aliphatic organic compounds.