The structure of methanol monohydrate at 160 K has been solved from powder neutron diffraction data by ab initio methods. The crystal is orthorhombic, space-group Cmc2(1) (Z = 4) with unit cell dimensions a = 4.64910(2) angstrom, b = 14.08464(7) angstrom, c = 4.69358(1) angstrom V = 307.340(2) angstrom(3) (rho(calc) = 1212.29(1) kg m(-3)) at 160 K. The structure consists of water-water chains, linked by ordered hydrogen bonds extending along the c-axis, which cross link methanol-water chains with disordered hydrogen bonds along the a-axis. These perpendicular chains form sheets which are stacked parallel to the b-axis. (c) 2006 Elsevier B.V. All rights reserved.