Several examples of dissolution-recrystallization processes at the nickel hydroxide electrode are reviewed. Some of them are very well known and have been studied for a few yearsin the case of Ni/Cd cells. The cycling of the ∝-type nickel hydroxide leads to the ∝→β transformation through dissolution of the a phase in the electrolyte (KOH) and recrystallization of the β phase from the solution. Further cycling of the resulting βex ∝phase causes an ageing effect which occursvia the solution (Oswald ripening). More recently, a strong ripening phenomenon has been observed by studying the behavior of nickel hydroxides cycling in Ni/H2 cells. By simulating the ageing of charged and discharged materials under hydrogen pressure inKOH media, it has been shown that in the absence of voltage, hydrogen cannot be responsible for the strong ripening effect. Synergetic effects between hydrogen and voltage have to be considered.