The Poisson-Boltzmann equation is solved numerically in cylindrical space to examine the effects of curvature upon the properties of the diffuse double layer at a charged nanotube in electrolytic solution. Simulations reveal increased double layer capacitance, especially for cylinders with radius less than 20 nm. The potential drop from the nanotube surface to the maximum tunnelling distance is therefore expected to be greater than for larger cylinders, providing a possibly enhanced electrochemical driving force for electron transfer and a possible partial cause for altered electrode kinetics at carbon nanotube modified electrodes. This effect is also predicted for cylinders of radius larger than 20 nm in solutions of low supporting electrolyte concentration. However, the effects on the observed electrode kinetics are predicted to be small. (C) 2009 Elsevier B. V. All rights reserved.