This book presents the most recent findings in science and technology of iron oxides based materials. It contains eight chapters written by research experts from different countries. The book covers recent results on superparamagnetic iron oxide nanoparticles used as contrast agents for molecular imaging and cell tracking; the synthesis and characterization of nanostructured iron oxides embedded in porous matrixes; the use of superparamagnetic nanoparticles in characterizing cardiac injury; application of iron oxide thin films in solar water splitting; the relation of photoresponse with different impurities in the iron oxide matrix; the use of coated iron oxide nanoparticles in cell and tissue engineering for designing strategies for cardiovascular medicine; and research on natural and man-made iron oxides nanoparticles focused on the natural iron oxides nanoparticles developed in plants and the impact of man-made iron oxide nanoparticles on the growth of plants. Additionally, the use of superparamagnetic iron oxide nanoparticles in magnetic resonant imaging, applied drug delivery, and photodynamic therapy are discussed. Finally, the application of both natural and synthetic iron oxides based adsorbents in arsenic removal is reviewed. For these characteristics, this book is useful for specialists working in multidisciplinary projects where iron oxides are involved, as well as to graduate students, and upper-level undergraduates undertaking research in this field.