Curing of the positive paste is the most time consuming technological procedure in the process of lead-acid battery manufacture. During curing the following processes take place: Pb oxidation, 3PbO - PbSO4 - H2O and oxide recrystallization, grid corrosion, improvement of the paste/grid contact, and drying of the plate. When the temperature is increased and an appropriate humidity cyclogram is chosen, the curing processes are enhanced which allows the duration of the curing process to be reduced from 72 to 48h. However, temperature rise is limited to 65°C because above this temperature, a transformation reaction of 3PbO • PbSO4 • H20 to 4PbO · PbSO4 begins. Through the technology we propose for paste preparation from 4PbO • PbSO4 and Pb304, batteries were manufactured with high initial capacity and cycle life longer than that of classical 3PbO • PbSO4 • H2O plates. 4PbO - PbSO4 formation during paste preparation allows elimination of the upper temperature limit of curing. The present paper is in itself an investigation of the processes during curing of3PbO · PbSO4 • H20 and 4PbO • PbSO4 (with Pb304) pastes at 93°C and water vapor inlet. It was established that 3PbO · PbSO4 · H2O istransformed into 4PbO • PbSO4 large crystals which are very slowly oxidized to Pb02. That is why such plates have low initial capacity. Curing of 4PbO PbSO4 pastes under these conditions proceeds very quickly (8-21h). Batteries manufactured with such plates have initial capacity equal to the rated one and cycle life considerably longer than that of batteries produced from 3PbO · PbSO4 • H20 pastes. © 1990, The Electrochemical Society, Inc. All rights reserved.