Ultrafine particles of CaCO3 were synthesized by dispersing the mixture of CO2 and N-2 into the Ca(OH)(2)/H2O Slurry with a micropore-plate. Because the micropore is micrometers scale, process of momentum transfer, mass transfer and reaction was significantly enhanced. The carbonation process of Ca(OH)(2)/H2O system was monitored with pH and conductivity. Operation conditions were investigated on the specific surface area of particles, such as initial slurry concentration and volume, gas flowrate and concentration, and temperature. The crystal structure of particles was characterized with BET, IR, TEM, SEM, etc. Results showed ultrafine particles were calcite with general shape of cube, whose size was about 40 nm and specific surface area was more than 25 m(2)/g. This preparation method is easy to operate. (c) 2006 Elsevier B.V. All rights reserved.