Novel trioctahedral Ni-smectites were synthesized hydrothermally from Ni-Si hydrous oxide at 125°-300°C under autogeneous water vapour pressure for 2h. With increasing temperature of hydrothermal reaction, adsorption of methylene blue (MB) increased from 0.20meq⋅g-1 to 0.76meq⋅g-1 between 125° and 175°C, but gradually decreased from 0.76meq⋅g-1 to 0.48meq⋅g-1 between 175° and 300°C. On heating, the specimen NS-04 synthesized at 200°C formed a porous material with mesopores and micropores indicating a maximum specific surface area (SSA) of 222m2g-1. Addition of fluorine decreased the MB adsorption and increased SSA. The mesoporous material from a precursory Ni-smectite NS-04 has a total SSA of 537m2g-1, a pore volume of 0.79 cm3⋅g-1 and an average pore diameter of 59A, which are significantly higher than those of conventional pillared clays.