Highly branched Pt-Ni nanoalloys with varied chemical compositions were prepared by one-pot solvothermal synthesis. The morphology, structure, composition and catalytic properties of Pt-Ni nanoalloys were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electrochemical cyclic voltammetry and chronoamperometry. The dendritic Pt3Ni nanoalloys exhibit markedly improved catalytic activity toward the electro-oxidation of ethylene glycol and glycerol in alkaline medium compared to commercial Pt black, benefitting from reasonable high surface areas and abundant structural defects. The chronoamperometric measurements indicated that the stability of dendritic Pt3Ni nanopalloy is better than both Pt black and Pt5Ni5 nanoparticles. Moreover, the catalytic activity of dendritic Pt3Ni nanoalloys was dramatically increased (7.5-fold) by increasing operation temperature from room temperature to 45 degrees C. The enhanced electrochemical properties of Pt3Ni represent promising candidates for highly active fuel cell catalysts.