In this study, we propose a model to simulate electrical conduction of single carrier organic diodes in the presence of a barrier for carrier injection and considering a field-dependent carrier mobility. An analytical expression for the internal electric field function, that simplifies operation with the resulting nonlinear equation system, is provided. Simulated results with this model are compared with those obtained from other existing approaches that assume simplifications. Current density versus voltage curves predicted by this model for diodes with different active layer thicknesses show good agreement with the experimental results. Copyright © 2010 John Wiley & Sons, Ltd.