Lead dioxide thin films and nanowires were prepared by electrochemical deposition using a 0.1 M Pb(NO3)(2) solution. alpha-PbO2 is deposited at pH 5.0, while beta-PbO2 is obtained at pH 0.0. Using pH 5.0, films of different thicknesses and nanowires of different lengths were prepared by varying the deposition charge (Q(dep)). The electrochemical reactivity of PbO2 is strongly dependent on the structure of the deposit. For PbO2 nanowires and thin films, only similar to 6 to 7% and 2-3% of the deposited material is electrochemically active, respectively. A detailed analysis of the reactivity of PbO2 with the deposition of PbO2 with the deposition charge was performed by assuming that r=aQ(dep)(b), where r is the percentage of reactive matter, and a and b are adjustable parameters. For PbO2 nanowires, b=-0.2 and the reactivity is almost independent of the deposition charge (and length of the nanowires). In contrast, for PbO2 thin films, b=-0.65 and the reactivity decreases rapidly with the reciprocal of the deposition charge. After 10 cycles, PbO2 nanowires and thin films exhibit almost the same activity.