Single crystal X-ray diffraction is the most powerful method available for determining the three dimensional structure of molecular materials in the solid state. However, it has always been viewed as a ground state, time averaged method of analysis that does not give information on what molecules look like when they are undergoing a chemical or photochemical reaction. This project sets out to change this situation, and introduce the 4th dimension of time into diffraction experiments so that it will be possible to determine the structure of molecules as they undergo a photochemical activation and see species that have lifetimes of a few microseconds of less. Using this technique it will be possible to make a molecular movie and watch molecular geometries change, in three dimensions, as the chemical process occurs. In order to undertake a successful time resolved (photocrystallographic) experiment it is necessary to pump the crystal with a pulsed laser and probe it with an X-ray beam from a synchrotron in a synchronised fashion so that the excited state structure is obtained.This has the potential to be a very important technique for understanding the processes that occur in opto-electronic materials when they are activated, and may help in the designe of new smart materials.