Alumina-pillared fluorine micas were prepared from synthetic highly layer-charged expandable fluorine mica and polyhydroxoaluminium solutions under different solution loadings (Al mmol in solutions per 1.0 g mica) in order to clarify the effects of solution loading on thermal durability and microporous properties. The intercalated Al content of the pillared micas increased with increased solution loading. The intercalated Al content (i.e. the pillar density) of the pillared micas influenced both the thermal durability and specific surface areas of the pillared micas. The pillared micas obtained from the high solution loadings showed better thermal durability than those obtained from the low solution loadings. Through micropore formation upon heating, the pillared micas exhibit cation exchangeability due to the liberation of residual Na+ ions from steric hindrance in the interlayer pillaring space. The amount of the exchangeable ions depends on the heating temperature of the pillared micas.