The study investigates the process of the electrical current passage in a system with non-uniform electric field under assured absence of injection. The cell has a special design, with the region of the strong electric field located far from metal electrode surfaces and the non-linearity of the current-voltage characteristics ensured solely by the field-enhanced dissociation. The characteristics were measured experimentally and studied numerically for dielectric liquids with different values of low-voltage conductivity; the results were compared. The computations were carried out on the basis of the complete set of electrohydrodynamic equations using commercial software package COMSOL Multiphysics. (C) 2016 Elsevier B.V. All rights reserved.