Two regimes of electrohydrodynamic flow are investigated for two groups of electrodes of various sizes in two liquids which differ greatly in viscosity. The mechanisms of these regimes are not connected with the change of the hydrodynamics of the flow (e. g. , with the transition from the laminar to turbulent region), but are explained by the change of the current-carrying mechanism from drift to convective. The nature of the electrohydrodynamic flow in the strongly and weakly nonuniform field is the same, and is clearly determined by the electrochemical processes near the electrodes.