Zeolite　P　was　synthesized　for　the　first　time　via　a　novel　water-bathing　route　at　90　C　using　scrubbed　diatomite,　sodium　hydroxide,　and　aluminum　hydroxide　as　precursor,　with　SiO2/Al2O3,　SiO2/Na2O,　and　H2O/Na2O　molar　ratios　of　7.43,　3.81,　and　80.00,　respectively.　The　as-fabricated　samples　were　characterized　by　means　of　scanning　electron　microscopy.　X-ray　diffraction,　and　nitrogen　adsorption　measurements.　This　study　showed　that　(i)　treating　the　diatomite　raw　material　with　sodium　hexametaphosphate　could　open　the　pores　in　the　diatomite　via　removal　of　the　clay　clogged　in　its　pores;　(ii)　tetragonal　mesoporous　zeolite　P　samples　with　a　surface　area　of　56-60　m(2)/g　could　be　generated　after　6-24　h　of　water-bathing　reaction　at　90　degrees　C;　(iii)　extension　of　water-bathing　reaction　time　could　improve　the　mesoporous　structure　of　zeolite　P;　and　(iv)　Ca2+　adsorption　capacity　of　the　zeolite　P　sample　was　about　300　cmol/kg.　Such　high-surface-area　porous　zeolite　P　could　be　used　as　an　effective　adsorbent　for　the　treatment　of　water　containing　calcium　and　magnesium　ions.　(C)　2010　Chinese　Society　of　Particuology　and　Institute　of　Process　Engineering,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.　All　rights　reserved.