The discharge performance of lead-acid battery is improved by adding multi-walled carbon nanotubes (MWCNTs) as an alternate conductive additive in Negative Active Mass (NAM). We report that MWCNTs added to the negative electrode, exhibits high capacity, excellent cycling performances at 10-h rate, high rate partial state of charge (HRPSoC) cycling and various rates of discharge. It significantly reduces the irreversible lead sulfate on the NAM, increases the active material utilization and improves the electrode performance. The improvement of capacity and cyclic performance of the cell is attributed to the nanoscale dimension of the MWCNTs as additive. Subsequent characterization using high resolution transmission electron microscopy and scanning electron microscopy were carried out to understand the influence of MWCNTs on the negative electrode of lead-acid battery. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.062301jes] All rights reserved.