A preliminary investigation was conducted on electrostatic inkjet phenomena. High voltage was applied between an insulative capillary tube filled with ion-conductive water and a metal plate electrode. Inkjet phenomenon was observed at the dark discharge under conditions of appropriate voltage application and water level. Although the electrostatic attractive Coulomb force is small, in the order of 10 μN at the voltage lower than the corona onset, it is large enough to separate a water drop against surface tension to the capillary tube at certain conditions. The diameter of the drop was about one millimeter. At the beginning of corona discharge, however, water mist was dispersed at wide angle from the tip of the tube due to the Coulomb repulsive force of charged mist. When the applied voltage was further increased, water mist became to be dispersed like spray, because the ionic wind prevented the separation and spread of the droplet. Application of adjusted pulse voltage can form a droplet of which formation is synchronized with the pulse. The diameter of the droplet depended on the applied voltage and the tube diameter. The droplet volume was in the order of several hundred picoliters. Preliminary printing on a paper was also demonstrated. This phenomenon is expected to be utilized for a new inkjet print head.