An investigation has been made of the effect of lignin and BaSO4 on the capacity and life of the negative plate. BaSO~ alone, lignin alone, and combinations of the two improved cycle life. Of the combinations tested, 0.5% BaSO4 and L0% lignin gave the greatest improvement on SAE cycle life tests. Lignin alone was as effective as the lignin-BaSO4 combination in highrate, low-temperature discharges. Lignin decreased the diameter Of the lead particles and passivated portions of the lead surface, so that lead sulfate crystal growth was away from the surface, leaving considerable open space in the mass of crystals at the end of discharge. Without lignin the lead particles were larger, more closely spaced, and lead sulfate grew solidly along the lead surfaces, so that there was little void space at the end of charge. Microscopic examination showed nothing to explain the beneficial effect of BaSO4.