Hexagonally　crystallized　CaCO3　materials　with　flower-like,　belt-like,　network-like,　coralloid,　and　hexagonal　and　rectangular　parallelepiped　morphologies　were　selectively　fabricated　using　the　surfactant　(cetyltrimethylammonium　bromide,　sodium　dodecyl　sulfate,　poly(N-vinyl-2-pyrrolidone　or　poly(ethylene　glycol)　(PEG))　mediated　solvo-　or　hydrothermal　strategy　with　CaO　powders　as　Ca　source　in　an　oleic　acid　(OA)/ethanol,　OA/ethylene　glycol　or　water　solvent,　respectively.　The　as-obtained　materials　were　characterized　by　means　of　the　techniques,　such　as　X-ray　diffraction,　thermogravimetric　analysis　and　differential　scanning　calorimetry,　Fourier　transform　infrared　spectroscopy,　high-resolution　scanning　electron　microscopy,　high-resolution　transmission　electron　microscopy,　selected-area　electron　diffraction,　and　N-2　adsorption-desorption　measurement.　It　is　shown　that　the　morphology　of　the　CaCO3　product　was　associated　with　the　nature　of　surfactant　and　solvent　and　solvo-　or　hydrothermal　temperature.　The　surfactant-free　fabricated　CaCO3　particles　were　cube-like　in　morphology.　The　rise　in　solvo-　or　hydrothermal　temperature　favored　the　enhancement　in　surface　area　of　the　CaCO3　product.　Among　the　as-fabricated　CaCO3　samples,　the　one　derived　hydrothermally　with　PEG　at　240　degrees　C　possessed　the　highest　surface　area　(134　m(2)/g).　Such　a　high-surface-area　wormhole-like　mesoporous　CaCO3　sample　could　decompose　below　800　degrees　C　to　mesoporous　CaO　with　high　surface　area　(110　m(2)/g).　This　reversible　regeneration　feature　makes　the　mesoporous　calcite　useful　in　gas　adsorption　and　separation　as　well　as　catalysis.　The　possible　mechanisms　for　the　multiply　morphological　CaCO3　formation　have　also　been　discussed.　(C)　2010　Elsevier　Inc.　All　rights　reserved.