Organic-inorganic perovskites have recently been shown to be potentially efficient and inexpensive photovoltaics. These materials undergo a series of structural transitions and it is our aim to understand the dynamics driving these transitions. This proposal requests time to study the dynamics driving the structural transitions in CH3NH3PbBr3 using the complementary selection rules Raman spectroscopy and neutrons. The proposal requests time on the MAPS spectrometer. A further proposal to use IRIS on this material is also being submitted in parallel.