The state of water in air-dry kaolin and the influence of aniline complexes (NSO 4·2An,MCl 2·2An, where MCu(II),Zn(II),An — aniline) on kaolin and water interaction has been studied by IR-spectroscopy. Accelerated dehydration of kaolin effected by aniline complexes with kaolin transition from plastic into clod-like state has been observed. Investigation of IR-spectra has shown that hydrated kaolin contains 3 types of water molecules characterised by different energy resources with the transition of a part of water into the state when weak bonds are formed between it and the surface-layer AlOH groups of kaolin, the effect being produced by the most active of the complexes, CuSO 4·2An. Thermal (800°C) and acidic treatment of kaolin destroys these groups and effects the transition of kaolin into amorphous state; as a result the character of kaolin and water interaction is sharply changed and the effect of the aniline complexes is no longer observed.