Microporous silica was prepared by selective leaching of the Al₂O₃ component from calcined kaolinite. The kaolinite was calcined at various temperatures from 400 to 1000°C for 24 h. It was then chemically treated with a 20 mass% H₂SO₄ solution at 90°C for 2 h and the effect of the calcining temperature was studied. The chemical composition of the acid leached product changed largely by elevating the calcining temperatures from 425 to 475°C owing to selective leaching of Al2O3 from metakaolinite and became almost SiO₂ composition above this calcining temperatures. With decreasing of Al₂O₃ content in the products, the specific surface area increased and became higher than 300m²g^-1. It further increased gradually with higher calcining temperature up to 700°C because of the increase of efficiency of selective leaching. The pore size distribution was calculated by the Horvath-Kawazoe method based on Ar gas isotherms and the slit-shaped pore size was about 0.6nm in width for all the products with irrespective to the calcining temperatures. Since the particle shape was preserved after the leaching treatment, those pores are considered to be formed in the interlayers of the SiO₄ tetrahedral layers largely preserving the original metakaolinite structure.