Na-Montmorillonite (Na-Mmt) was melt-intercalated with alkylamine and quarternized ammonium salts of sulfonated polystyrene ionomers (SPS) with no other organic modification. Mixtures of SPS and polystyrene (PS) also exhibited similar intercalation, indicating that the ionomer was an effective compatibilizer for a non-polar polymer such as PS. The materials were mixed in a co-rotating, non-intermeshing twin-screw extruder. The intercalation was relatively insensitive to the melt processing conditions. The key variable appeared to be the ratio of charge between the ionomer and the clay. Intercalation was assessed by wide angle X-ray diffraction and transmission electron microscopy. (c) 2005 Elsevier Ltd. All rights reserved.