The results of performance tests of the battery modules and single cells developed as part of the Japanese national project for energy storage are reported. Two types of 2 kWh-class modules for stationary use have almost attained the target of initial performance, but the cycle lives are still about 1000 cycles. Similarly, two types of 3 kWh-class modules for EV application have achieved the targets of 150 Wh/kg and 400 W/ kg. The energy density of each single cell exceeded the target by about 20%, but in the case of the single cells of cylindrical shape, the target could not be achieved because of dead space in the modules. Cell performance under severe conditions of -20 degreesC or continuous discharge at 1.0C were suitable for practical use. The influence of the dynamic stress on cycle performance is shown to be slight, but the subject of energy storage at high temperature is pointed out in the case of the cells containing Mn oxide cathode. (C) 2003 Elsevier Science B.V. All rights reserved.