New reflections appear in the powder X-ray diffraction patterns of Ni–Al–Cl LDH films that have been subjected to repeated voltammetric scans in basic electrolytes (pH⩾12). They are attributed to the formation of new phases, one of which is β-Ni(OH)2. The intensities of the d 003 and d 006 reflections of the LDH layer were also reduced. This was not observed for Ni–Al–Cl LDH films that were simply soaked in basic solutions or cycled in pH 8 buffer electrolyte solutions. The XRD pattern of Ni–Al–CO3 LDH films was not affected by voltammetric scanning in basic electrolyte.