A novel complex loose-tube (fiber-in-tube) morphology (Nb)-SnO2 has been prepared by conventional, single-needle electrospinning, and a mechanism for the formation of fiber-in-tube structures is proposed. The presence of niobium drives the morphology of electrospun tin oxide from dense fibers to loose tubes by enhancing the Kirkendall effect where precursor salts diffuse to the fiber surface during calcination. The highest electronic conductivity (0.02 S cm(-1)) of the cassiterite structured niobium-doped tin oxides is observed with 5 wt % Nb doping. The loose-tube morphology materials have been further functionalized by depositing Pt nanoparticles prepared by a microwave assisted polyol method, and the samples examined by electron microscopy and studied for their electrochemical properties. The electrochemically active surface area of 13 wt % Pt on Nb-SnO2 is >50 m(2) g(-1), and is more stable to voltage cycling than Pt/C.