We have identified a new material Ba2LuMoO6 where cation ordering between Lu and Mo leads to a distribution of S=1/2 Mo5+ cations on the lattice points of a regular cubic fcc lattice. Dc magnetic susceptibility measurements and neutron diffraction data indicate the absence of long range magnetic ordering to 2 K despite the presence of strong antiferromagnetic interactions. The observed loss of paramagnetic moment on cooling below 50 K and the presence of a frequency dependent magnetic transition in the ac susceptibility all suggest the formation of a valence bond glass. We request muon beamtime to confirm this assignment and to probe this exotic electronic state as a function of temperature between 2K and 120K.