The structure and morphology of electrochemically deposited calcium carbonate have been investigated as a function of temperature, magnesium ion concentration, organic inhibitors, and deposition potential. At 25 degrees C, microcrystals of calcite grew with their [104] planes parallel to the electrode surface. In the presence of magnesium chloride, a mixed phase of calcite and magensium calcite, as well as aragonite, was formed. Organic inhibitors varied in their effectiveness in inhibiting calcite formation, e.g., 2-phosphonobutane, 1,2,4-tricarboxylic acid (PBTC) performed better than ethanediphosphonic acid (EDPA).