Earth-abundant material for solar-water splitting typically show lower efficiency than noble and rare catalysts. Nanostructuring and proper material design can largely improve the performances of low-cost electrocatalysts, opening the route towards a profitable mass production. Here, we report a quantitative investigation of oxygen evolution reaction (OER) on Ni-based nanowalls (NW) electrodes. NiO or Ni(OH)2 NW film (200 or 400 nm thick) are produced by chemical bath deposition followed by calcination at 350°C. Morphology and chemical arrangement of NW were studied, before and after OER, by scanning electron microscopy, energy dispersive X-ray analyses and X-ray photoelectron spectroscopy. OER catalytic activity was investigated by electrochemical measurements under alkaline conditions (1M KOH), demonstrating a stable overpotential of 345 mV at 10 mA/cm2, a Tafel slope of 48 mv/dec and an O2 …