A thermo-electro-hydro-dynamic model is developed to examine the effects of fluid slip on electrokinetic energy conversion in nanofluidic channels. The optimum electrokinctic devices performance is dependent on a figure of merit defined in terms of hydrodynamic conductance, streaming effects and electrical conductance of slip nanochannels. These phenomenological coefficients are all enhanced by the fluid slip as compared to those without slip effects. The net result is an increased figure of merit and thus an enhanced electrokinetic devices performance, particularly in nanochannels with a high ratio of slip length to channel height. (C) 2007 Elsevier B.V. All rights reserved.