The interest in the design and controlled fabrication of mesoporous carbon nanospheres emanates from their tremendous potential applications in adsorption, energy conversion and storage, gene therapy, and catalysis. Here, we report the synthesis of uniform N-doped mesoporous carbon spheres with tunable particle size from 40 to 750 nm by a one-pot soft template method. The synthetic method also allowed the preparation of N-doped microporous or mesoporous hollow carbon spheres. While all the resulting materials showed favourable electrocatalytic activity, the metal-free N-doped mesoporous hollow carbon spheres with particle size of ∼150 nm, in particular, exhibited the highest activity. ; Tianyu Yang, Jian Liu, Ruifeng Zhou, Zhigang Chen, Hongyi Xu, Shi Zhang Qiao and Michael J. Monteiro