Vermiculite (VER) was exfoliated to be used as organovermiculite nanofiller(ODA/VER) for polypropylene (PP)/VER nanocomposites. We used three procedures. PI: low-temperature intercalation of melted octadecylamine (ODA) led to the regular bilayer arrangement of organic molecules in the interlayer space. P2: mechanical exfoliation of ODA/VER by jet milling decreased the crystallite size. P3: chemical exfoliation using an oxidizing agent potassium persulfate and subsequent intercalation with ODA created a mixture of monolayer and bilayer arrangements of organic cations in the interlayer. The thermal compounding of the organovermiculites (4 wt.%) with maleated PP at 30 and 50 rpm caused the partial deintercalation of the organovermiculite and organovermiculite pretreated with the oxidizing agent. The jet milled ODA/VER was very well dispersed within PP matrix. Thermal stability of PP and PP/VER nanocomposites with differently exfoliated ODA/VER nanofillers was evaluated by thermogravimetric analysis. (C) 2008 Elsevier B.V. All rights reserved