Fabrication of high-performance fluid catalytic cracking (FCC) catalysts is suffering from the shortage of high-quality kaolin that has long been used as matrix or starting material for synthesizing FCC catalysts. This work aimed at exploring the potential of rectorite, a natural aluminosilicate mineral, to substitute kaolin for preparing FCC catalysts through in-situ synthesis technique. The physicochemical properties of a rectorite mineral, including its chemical composition, structure, thermal behavior, and chemical reactivity, were systemically investigated and compared with those of commercial kaolin. The results showed that the rectorite mineral suitably treated could substitute kaolin for synthesizing FCC catalysts. Moreover, we had shown that a hydrothermally stable ZSM-5/rectorite composite in which ZSM-5 crystals of ca. 2 mu m in size were overgrown on preformed rectorite substrate could he synthesized using the rectorite mineral calcined at 800 degrees C as raw material. When used as FCC additive, the obtained ZSM-5/rectorite composite demonstrated enhanced light olefin (ethylene and propylene) yields. (C) 2010 American Institute of Chemical Engineers AIChE J, 56: 2913-2922, 2010