The title compound (Ph2PO)2 is analyzed by single crystal X-ray diffraction analysis. The crystals are monoclinic, space group P2(1)/n with a = 9.5112(19) angstrom, b = 11.161(2) angstrom, c = 9.5487(19) angstrom, alpha = 90 degrees, beta = 91.65(3)degrees, gamma = 90 degrees, V = 1013.2(3) angstrom(3), Z = 2, F((000))=420, Dc = 1.319g cm(-3), mu = 0.232mm(-1), the final R = 0.0818, and wR=0.2259. A total of 7954 reflections were collected, of which 1758 were independent (R-int=0.0542). In the crystal packing diagram, intermolecular C-H center dot center dot center dot O hydrogen bonds stabilize the solid state of the title compound.