The demand of green energy will be the major issue in this 21 century. The researchers are trying to develop green energy using a variety of ways. Among various forms of green, safe and sustainable energy, hydrogen is considered as the best one due to its inexpensiveness and no pollution to the environment. Moreover, the abundance of sunlight and water resources are great assets for us to generate hydrogen fuel. The research has incased on water splitting after the development of nanotechnology but the various chemical routs of nanoparticles synthesis are toxic to the human and the environment. In recent years, many nanoparticles are synthesized by green methods utilizing plants and other microbes. Some papers are available on the applications of water splitting using these green nano particles. The future of this research is very bright and to increase the further research in this area, a review is written. The present article describes the state-of-the-art of water splitting using green nanoparticles. The attempts are made to describe the various methods of nanoparticles syntheses, their optimizations and applications in hydrogen generation. Besides, the efforts are also made to discuss the working mechanism and future challenges and perspectives. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.