Ferredoxin (Fd) are small [Fe‐S] cluster containing proteins, which act as the first soluble acceptors of electrons on the stromal side of the chloroplast electron transport chain. In addition to their primary function in photosynthesis, Fds are also involved in a number of other essential metabolic reactions, including biosynthesis of chlorophyll, phytochrome and fatty acids, assimilation of sulfur and nitrogen as well as redox signalling and maintenance of chloroplast redox balance. Therefore, Fds are crucial determinants of the electron transfer between the thylakoid membrane, and the soluble enzymes dependent on these electrons. We describe the current knowledge on the structure and function of the various Fd isoforms present in chloroplasts of higher plants, and then discuss the processes involved in oxidation of Fd, introducing the corresponding enzymes.