Pyrazine-I is stable < 302 K, phase II exists from 302-310 K, and phase III from 310-324 K. The known phase-I forms an ordered structure. It is thought that structures of phases II & III are closely related, but neither crystal structure has been determined. Raman measurements show that pyrazine undergoes phase transition at 1 GPa. Tetramethylpyrazine has also been studied using Raman spectroscopy to 4 GPa. Pressure-induced phase transitions take place at 1.2 and 2.2 GPa. The aims of this proposal are to characterize pyrazine II & III and survey the low temperature behaviour of the compound; to study the effect of pressure on pyrazine to 5 GPa on PEARL, determining the structure of the new high-pressure phase formed at 1 GPa; to study and the effect of pressure on tetramethylpyrazine to 5 GPa on PEARL; obtain crystal structures of the high pressure phases formed at 1.2 & 2.2 GPa.