Nickel metal hydride (Ni/MH) is presently the most promising battery system for electric and hybrid vehicle propulsion in the short and mid-term. This paper presents the results obtained in the development of prismatic Ni/MH batteries for high power, mainly hybrid vehicle, applications. Valve regulated Ni/MH cells rated at 25 and 60Ah have been designed and assembled using improved positive and negative electrodes. Both types of cells showed excellent high rate discharge capability and fast rechargeability and a satisfactory charge retention when stored and cycle life under deep cycling and hybrid vehicle working conditions. On the other hand, energy and power efficiency ratios were improved in the 60Ah cells.