This study reports a delicate electroless approach for the deposition of RuO·HO nanoparticles on the VO ·HO nanowires and this method can be extended to deposit RuO·HO nanoparticles on various material surfaces. Electrochemical characterizations, including linear sweep voltammetry (LSV), electrochemical quartz crystal microbalance (QCM) analysis and rotating ring-disc electrode (RRDE) voltammetry, were carried out to investigate the growth mechanism. The deposition involves the catalytic reduction of dissolved oxygen by the V species of VO ·HO, which drives the oxidation of RuCl to proceed with the growth of RuO·HO. This core/shell VO ·HO/RuO·HO shows a better catalytic activity of the oxygen reduction reaction (ORR) than RuO·HO, which is ascribed to the pronounced dispersion of RuO·HO. Such an electroless approach was applicable to the preparation of a RuO-based nanoparticle suspension as well as the deposition of nanocrystalline RuO·HO on other functional supports like TiO nanowires. The thus-obtained RuO-decorated TiO nanorods exhibit significantly an enhanced photoactivity toward photoelectrochemical water oxidation. The versatility of the current electroless approach may facilitate the widespread deployment of nanocrystalline RuO·HO in a variety of energy-related applications.