The synthesis or amorphous calc~um carbonale in the reacllons oi cslcn~m hydroxide suspension - CO1 systcni !.;is studied by uslng rneasulemel~ts of eleclrical conductivity, x-ray diftractorneter and t~ansmission eleclron microscope. The m~tial product of reactious was noncrystalline shape oI amorphous calcium carbo~iale confirmed by x-ray diffraction analyses. The amorphous calcium carbonate covered lhc surlace of calcium hydroxldc grains. Tlic electrical conductivity of suspension dec~eascd dramatically when the amorphous calcium carhonate was synlliesizcd. A portion or the amorplious calcmm carbonale clia~iged ilito [he chain calcite as an intermcdrate product. Thc continuo~~cso nrluctivity measurements of suspension were ahle to delennine the starting point of the synthesis and the mechallism of carbonation process