Molybdenum containing glasses have many potential applications. However, there is little information available on the structural role of molybdenum in glasses, and the limited information is contradictory. Neutron diffraction has the potential to clarify this subject. We have performed a brief neutron diffraction test measurement on a lead phosphomolybdate which shows that molybdenum is predominantly tetrahedral, but with a smaller number of octahedral sites. We wish to use GEM to follow this test up with a full set of measurements on glasses from this system.