A new molybdenotungsten monophosphate, Li0.5MoWO3(PO4)(2) has been synthesized that crystallizes in the space group P2(1)/m with a = 7.735(1) Angstrom, b = 12.655(1) Angstrom, c = 8.324(1) Angstrom, b = 105.97(1)degrees. The [MoWP2O11](infinity) framework is isotypic with that previously observed for LiMo2O3(PO4)(2), lithium being located in six-sided tunnels running along (a) over right arrow with an octahedral coordination. This phase differs from LiMo2O3(PO4)(2), by the absence of lithium in the tetrahedral sites, showing that a significant lithium nonstoichiometry is possible. The stability is discussed with respect to other lithium monophosphates LiMoWO3(PO4)(2) and Li0.2Mo2O3(PO4)(2) that have different original structures.