We examined the correlation between the internal structure and the ionic conductivity behavior of lipophilized smectic clay (SPN)/polymer nanocomposites having various dispersed morphology of the clay layers. Both polystyrene (PS)/SPN and poly(methyl methacrylate) (PMMA)-co-acrylamide (AA) (99/1 mol rate)/SPN intercalated nanocomposites, which have finer dispersion of the clay layers, exhibited higher ionic conductivity rather than the other systems such as PMMA/SPN nanocomposite with stacking layer structure. The finer the dispersed morphology the higher was the conductivity of the nanocomposites. (C) 2000 Elsevier Science Ltd. All rights reserved.