In this work sodium montmorillonites have been modified with fatty acids (oleic acid, undecylenic acid) and with various quaternary ammonium salts (ODTAB, HDTAB, etc.), to achieve a hydrophobic material character, to facilitate an incorporation and distribution of the layered silicate as filler material in a polyolefin, and make the use of a compatibilizer obsolete. To achieve that two different modification methods were used. The fatty acids have been bound by polar interactions of the acid’s carboxylic group and the hydroxy groups on the surface of the montmorillonite. In parallel an ion exchange was conducted and the sodium ions located in the interlayer space were substituted by quaternary ammonium salts. The combination of both modification processes led to a change in the material character that has been investigated with various characterization methods. The amount as well as the thermal stability of the adsorbed and intercalated surfactant molecules has been determined with thermogravimetric analysis (TGA). To verify the presence of the fatty acids and the ammonium salts on the surface and the interlayer space of the montmorillonite Fourier transform infrared spectroscopy (FTIR) was used. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) were used to determine physical properties such as the increase of the basal spacing after the modification process. The modified silicate has been incorporated in a polymeric matrix (polypropylene) and characterized. The results of the SAXS measurements indicate the successful modification of the layered silicate.