A 3D nanoporous graphitic carbon (g-C) material is synthesized by using an adamantane (C10H16) flame, and utilized to support a Pt50–Ru50 alloy catalyst. The physico-chemical properties of the Pt50–Ru50/3D nanoporous g-C electrode are examined by a range of spectroscopy techniques as well as Brunauer–Emmett–Teller surface area analysis. Cyclic voltammetry measurements are used for electrochemical characterization of the Pt50–Ru50/3D nanoporous g-C electrode. The electrochemical investigations show that the supported Pt50–Ru50 has excellent activity and stability towards methanol electro-oxidation. Good CO tolerance is also shown, and considered to be due to the presence of Ru nanoparticles. It is proposed that Ru is able to promote the oxidation of strongly adsorbed CO on Pt by supplying an oxygen source: Ru(OH)ad. Moreover, the presence of 3D nanopores in the g-C support may also contribute to the observed higher current density by virtue of the easy transport of methanol and the oxidation products through these nanopores.