Enhancing the safety and durability of the techniques used to generate nanoparticles (NPs) is an important component of green nanotechnology. Conventional techniques of creating nanoparticles are complex, dangerous, and expensive, putting both humans and the environment at risk. To avoid these risks, scientists created calcium oxide nanoparticles (CaO-NPs) using biopolymers produced from bacteria, plants, and mushrooms. For example, reaction circumstances have a major impact on the creation of CaO-NPs, which influences their dimensions, functionality, and morphology. Furthermore, it is possible to synthesis CaO-NPs in an environmentally friendly manner, which has shown promise in a variety of domains such as biofuel production, refractory additives, adsorption, antimicrobial characteristics, Cr(VI) removal, and oil trans esterification. Participants in this study looked at numerous plant species and their constituent parts that were used in the production of CaO-NPs. The book included a variety of CaO-NP topics, including as synthesis, functionality, description, and clean production techniques. It was mentioned that they are still in use.