The microporosity of Al-pillared Li-montmorillonites with different layer charges obtained by thermal treatment at different temperatures was studied by nitrogen adsorption/desorption at -196 °C. A correlation was observed between the decreasing sorption capacity of samples derived from lithiated precursors heated at ever increasing temperature and the increasing contribution of the collapsed pyrophyllite-like areas inactive in pillaring. The dominant micropore radius remained below 3.5×10^–1 nm for all pillared samples, showing that, contrary to the common belief, the layer charge reduction by Hofmann-Klemen effect fails to bring about substantial changes in the lateral interpillar distances.