A simple and soft synthesis method, namely the polyol route, is proposed to synthesize RuXIr(1-x)O2 mixed-oxide nanoparticles deposited on a high surface area carbon support, with controlled size and size distribution, and composition. The samples are characterized by TGA, XRD, TEM, XPS and Raman analyses. Their behaviors as supercapacitors and catalysts for oxygen evolution reaction (OER) have been investigated in 0.5 M H2SO4 medium. it was demonstrated that pure RuO2 presented the highest super capacitive property, and that addition of iridium leads to decrease this property. On the other hand, pure RuO2 presented the lower onset potential for OER, but tended to be passivated as the potential was increased. Addition of iridium led to limit or to avoid the catalyst passivation and to increase the activity at high potential, but also to shift positively the OER onset potential. (C) 2016 Elsevier B.V. All rights reserved.