Nanoparticles of CuGaO2delafossite were successfully synthesized from the sol – gel process by controlling the atmospheric conditions at 850 °C. The average size of CuGaO2nanoparticles of ∼40 nm was determined by transmission electron microscopy. Note that the thermodynamically stable conditions for CuGaO2delafossite synthesis are 1100 °C and 1200 °C in nitrogen and air atmosphere, respectively, while our methodology stabilizes the CuGaO2particles in the nano-metric region at low temperature (i.e. 850 °C). Moreover, delafossites CuGaO2nanoparticles show very interesting bifunctional catalytic activity in the electrolysis of water with O2and H2generation at anodic and cathodic potentials respectively. The current densities of CuGaO2nanoparticles as the bifunctional catalysts were found to be 15 mA/cm2and 18 mA/cm2for H2and O2generation, respectively, using 0.5 M KOH solution as an electrolyte versus Ag/AgCl electrode. © 2016