Ruthenium nanoparticles (RuHT, RuPET and RuPA) were prepared by hydrazine hydrate reduction of RuCl3 and stabilized by the self-assembly of organic molecules (hexanethiol, phenylethanethiol and phenylacetylene). The sizes of these Ru nanoparticles were carried out by transmission electron microscopic measurement, with the average core sizes of 2.8 +/- 0.6 nm, 3.1 +/- 1.2 nm, and 3.1 +/- 1.1 nm, respectively. The structures and properties of these Ru nanoparticles were further examined and verified by UVevis, FTIR, 1HNMR, XPS and fluorescent measurements. The performance of the supercapacitor was characterized by cyclic voltammetry, constant-current charge-discharge, and electrochemical impedance spectroscopy. Ru nanoparticles showed enhanced supercapacitor behaviors as compared with blank electrodes. The Ru nanoparticles for supercapacitors in the H2SO4 electrolyte exhibited areal capacitances of 347.8, 304.9 and 229.1 mF cm(-2) for RuPET, RuPA and RuHT at a scan rate of 10 mV s(-1), and specific capacitances for 344.4, 249.3, 230.0 F g(-1) for RuPET, RuPA and RuHT at a current density of 0.5 A g(-1), respectively. The interfacial bonding between ruthenium and the outlayer organic ligands and varied ratio of ruthenium in high valence might be the reasonable explanation for the capacitance difference. (c) 2018 Elsevier Ltd. All rights reserved.