Electrocrystallization of PbO2 on glassy carbon electrodes was studied in 1 M HNO3 + 0.1 M Pb(NO3)(2) using cyclic voltammetry rotating disk electrode experiments, chronoamperometry, and scanning electron microscopy. In order to explain the experimental curves, a new theory of three-dimensional nucleation and progressive growth was developed and applied to analyze the experimental chronoamperometric curves. Numerical approximations led to the determination of kinetic parameters.