Motivated by increasing interest in the properties of molecular and associated liquids under extreme conditions we have been developing new instrumentation to enable in-situ optical spectroscopies up to high-pressure at variable temperatures. We are particularly interested in the properties of aqueous solutions where combinations of optical spectroscopy and neutron diffraction has led recently to substantial new insight into the nature of the hydrophobic association and the structure of water surrounding simple amphiphilic molecules. New high pressure cells have now been tested up to 15 kbar and we are continuing work on the properties of liquids and solutions up to supercritical conditions.