Nickel-iron (Ni-Fe), nickel-cadmium (Ni-Cd), nickel-hydrogen (Ni-H-2), nickel-metal hydride (Ni-MH) and nickel-zinc (Ni-Zn) batteries employ nickel oxide electrodes as the positive plates, and are hence, categorised as nickel-based batteries. This article highlights the operating principles and advances made in these battery systems during the recent years. In particular. significant improvements have been made in the Ni-MH batteries which are slowly capturing the market occupied by the ubiquitous Ni-Cd batteries.