Electrodes 0.5 mm thick (i.e. much thinner than conventional ones) and suitable for lead-acid batteries were prepared by using a special pasting procedure that allows plate thickness to be readily controlled. Novel rolled grids of Pb-Sn-low Ca alloys (0.35 mm thick) were used as substrates. Preliminary galvanostatic corrosion tests of the grids revealed an increased corrosion rate relative to conventional casted grids of Pb-Sn alloys (1 mm thick). Cells made with these thin electrodes were cycled under different discharge regimes and the active material at different charge/discharge cycling stages was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis. At a depth of discharge (DOD) of 100%, the cell exhibited a premature capacity loss after the fifth cycle and delivered only a 20% of its nominal capacity after the 10th. By contrast, cycling performance of the electrode was significantly improved at a DOD of 60%. The capacity loss observed at a DOD of 100% can be ascribed to a rapid growth of PbSO4 crystals reaching several microns in size. Such large crystals tend to deposit onto the grid surface and form an insulating layer that hinders electron transfer at the active material/grid interface. For this reason, the cell fails after few cycles in spite of the high PbO2 content in the positive active material (PAM). On the other hand, at 60% DOD the submicronic particles produced after formation of the PAM retain their small size, thereby ensuring reversibility in the PbO2 double left right arrow PbSO4 transformation. (C) 2003 Elsevier B.V. All rights reserved.