Lead dioxide obtained by using various methods in combination with particles ranging from nanometric to micrometric size was tested as positive active material in lead-acid cells. The structural and textural properties of the material were determined by using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM), N2 adsorption measurements and thermogravimetric analysis (TGA). Thin lead dioxide positive electrodes were prepared with obtained materials by spray deposition technique and were subjected to cycling tests. The combination of a small particle size (in the nanometric range) and the presence of water strongly bound to the lattice is essential to ensure a high utilization of the active material and good cycling properties of the positive electrode. Therefore, appropriate nanometric materials provide an effective method for increasing the efficiency of the active material in lead-acid batteries.