explores various synthesis methods of iron and iron oxide nanoparticles, with an emphasis on green synthesis – a sustainable and eco-friendly method. The book investigates a range of alternative routes to the synthesis of iron-based nanomaterials, such as using microorganisms (fungi, bacteria, actinomycetes), algae, green plants, and various biocompatible green reagents such as biopolymers, cellulose, and biomass. Furthermore, the effects of various parameters used in the green synthesis approach are examined in order to provide a clear image of the physicochemical features of the nanomaterials created.