Alkaline rechargeable batteries represented by Ni-Cd and Ni-MH batteries are expanding their market, continuously meeting an increasing demand. Approximately 30 years have elapsed since the first sealed Ni-Cd battery was commercialized for consumer use, and the production of these alkaline batteries is still expanding. The high power performance and good cost performance of these batteries are the outstanding features, which are leading to new battery applications. Continuous R&D of many researchers and engineers has improved these features. Since first coming to the market in 1990, Ni-MH batteries have been extending their application as power sources for portable advanced information and communication equipment. Improvements in electrode materials and other components have increased the energy density of current Ni-MH batteries to values of 91 Wh/kg and 340 Wh/l. Recently, novel metallic alloys for hydrogen storage have been proposed to increase their capacity further, and further improvement in the performance of these batteries is expected.