Abstract: Novel polymer-clay compositions were synthesized by neutralizing hydrogen montmorillonite and hydrogen kaolinite with amine-terminated polystyrene. The latter was obtained by the amide ion-initiated polymerization of styrene in liquid ammonia at −33°C. The neutralization reactions were carried out in methyl ethyl ketone, acetone, N,N-dimethylformamide and their aqueous solutions. As a result of their chemical modifications, the clays change from hydrophilic to hydrophobic, organophilic substances. Polystyrene-montmorillonite compositions containing about 50 per cent by weight of combined polymer formed dispersions in hydrocarbon oils which were similar to high temperature lubricating greases. The basal spacings of the organo-montmorillonites indicate the deposition of a polymer layer one molecule thick.