The sealed Ni/MH batteries with carbon nanotubes (CNTs) in the positive electrodes were assembled. The overall characteristics of Ni/MH batteries were investigated at different charge–discharge cycles at room temperature. The high-rate discharge performance of the Ni/MH battery was improved by the addition of CNTs in the positive electrode. Under high-rate discharge conditions, the batteries with CNTs added in the positive electrodes exhibited much better cycling stability, higher discharge voltage, and high-rate capability. The increase in internal resistance of the batteries with CNTs was lower than that of the batteries without CNTs during charge–discharge cycles. The addition of 0.5wt.% CNTs was proved a desired amount to modify the batteries performance at the high discharge rates. Too much CNTs contributed no effect in the improvement of overall performance of the batteries.