Copper sulphate pentahydrate is one of the iconic substances of chemistry. The characteristic dark blue colour is the result of the water present: four molecules are coordinated to the copper and one is present as water of hydration. The water is readily lost on heating to give the trihydrate, monohydrate and the anhydrous form. The hydrogen bonding network is complex and conventional vibrational spectroscopy is hampered by its inability to determine all of the modes. The aims of this proposal are twofold: firstly to study how the hydrogen bonding changes as the water is progressively removed and secondly to use the normalised intensity of the H-O-H bending mode at ~1600 cm-1 to provide a calibration for other INS studies that involve adsorbed water.