Intercalation compounds of layered niobate K4Nb6O17 with organoammonium ions adsorbed 2,4-dicholorophenol and phenol dissolved in water. Their adsorption properties were greatly influenced by the organoammonium species pre-intercalated; modification by dioctadecyldimethylammonium ions gave peculiar affinity for 2,4-dichlorophenol.