Fluorine micas having different grinding times were allowed to react with titania sol prepared by hydrolyzing titanium tetraisopropoxide (TTIP) with hydrochloric acid in order to clarify the influence of grinding upon reactivity of synthetic fluorine micas [M0.8Mg2.2Li0.8(Si4O10)F-2(M = Na, Li)]. Prolongation of grinding time promoted delamination and fineness of host mica crystals, resulting in increasing specific surface area. The heating weight loss and intensity of IR absorption bands around 1600 and 3400 cm(-1) also increased with increasing grinding time, indicating the increase in absorbed water on ground mica particles. Properties of titania pillared fluorine micas depended on grinding time of host micas. Specific surface areas and titania contents of pillared fluorine micas increased with increasing grinding time, so that the effect of interlayer cations (Na+, Li+) upon complex formation of titania pillared micas almost diminished. When host mica crystals were larger, the reaction occurred mainly in the interlayer region. However, when host mica crystals were ground to be finer, the reaction on external surfaces of ground particles occurred simultaneously along with intercalation. These results show that mechanochemical effects resulted from grinding have the profound influence on the formation and properties of titania pillared fluorine micas.