A new type of ink jet system is proposed on the basis of electrohydrodynamic (EHD) effect. On the application of high DC electric fields to some insulating fluids, a fluid jet with a velocity of about 1 ms⁻¹ is generated from the positive electrode as a bulk flow. By controlling the EHD flow to issue across the free surface, the ink jet device is developed, of which the nozzle unit is simply composed of a needle electrode and capillary. When the fluids are subjected to high electric fields, the ink jet is generated above a critical threshold and the height increases with increasing voltage. The critical voltage strongly depends on the nozzle geometry. The height of ink jet at high voltages increases with decreasing viscosity and conductivity of fluids. The performance of ink jet based on the EHD jet can be improved by a combination of designs of nozzle geometry and material functions.