The rehydration of potassium acetate-intercalated kaolinite has been followed using a combination of X-ray diffraction and Raman microscopy. Dehydration of the fully expanded potassium acetate-intercalated kaolinite with initial d(001) spacing of 13.88 Angstrom, in an atmosphere of nitrogen, shows the presence of three expanded kaolinite phases with d(001) spacings of 11.47, 9.6, and 9.2 Angstrom X-ray diffraction shows the existence of six expanded phases after one minute of rehydration with d spacings of 14.13, 11.56, 11.04, 9.88, 8.90, and 8.55 Angstrom. Rehydration is rapid with the intercalation complex rehydrating in less than 21 min. Raman spectroscopy shows hydroxyl stretching bands at 3632 cm(-1) assigned to the inner hydroxyl and at 3601 cm(-1) attributed to the inner surface hydroxyl hydrogen bonded to the acetate ion when the intercalation complex is heated to 300 degrees C under an atmosphere of nitrogen. The position of the inner hydroxyl band is observed at 3630 cm(-1) in the 298 K spectra, providing the intercalated kaolinite is not exposed to air. Phase changes of the intercalation complex are determined using the changes in intensity of the inner surface hydroxyl stretching bands. Phase changes are also observed through changes in intensity of the C=O, C-C, and OCO Raman modes.