The electrochemical reaction of Zn is investigated by scanning electron microscopy and transmission electron microscopy. Zn films are used as anodes, loaded at DC voltages of 10-200 V in distilled water at 20 degrees C. Zn ions diffuse from the anode and are coupled with OH ions to form spindle-like ZnO particles of 1-2 microns on the cathode or on a permeable paper barrier placed between the anode and cathode. Formless layers, which are composed of fine ZnO crystallites of several nanometers or less in size, form on the cathode in the water at lower OH ion density before the growth of the spindles. They become spindle-shaped after only a few minutes of water bath treatment at 60 degrees C.