The structure of a liquid crystal of 4-cyano-4′-n-undecyloxybiphenyl (C24H31NO) is determined by X-ray diffraction. The compound crystallizes in the monoclinic crystal system (space group C2/c) with the unit cell parameters a = 84.108(7) Å, b = 7. 159(2) Å, c = 6.922(2) Å, and β = 91.6(4)°. The structure has been solved by direct methods and refined to the residual index R1 = 0.067. Both phenyl rings are almost planar, and the dihedral angle between these rings is 31.5(6)°. © 2003 MAIK "Nauka/Interperiodica".