This paper presents a mathematical model for the electrochemical impregnation of nickel hydroxide in the type of porous nickel plaque used commonly in the positive electrode of Ni/Cd and Ni/H-2 cells. The model includes the transport of Ni2+, NO3-, OH-, and H+ ions, the electrochemical reduction of NO3-, and the homogenous acid/base and precipitation reactions. The effect of plaque thickness, plaque tortuosity, and applied current density on the time-dependent porosity distribution and on the uniformity of Ni(OH)(2) loading are discussed. Predictions for both constant-current and constant-potential operating conditions are presented. It is shown that a change in tortuosity from 1.6 to 3.0 can yield a 27% decrease in uniformity at 30 mA/cm(2) for a 0.075 cm thick plaque at 1.6 g/cm(3) of void loading. It is also shown that when the current density is changed from 30 to 40 mA/cm(2), the uniformity decreased by 20% for a plaque of the same thickness with a tortuosity of 1.6 at the same loading. The model could be used to develop quality-control tools to insure a uniformly loaded plaque during electrochemical impregnation.