A single crystal of the most commonly used antifreezing agent, ethylene glycol (m.p. 261.6 K), was grown in situ at 220 K with the help of a miniature zone melting procedure using an IR-laser beam. Crystallog. data and at. coordinates are given. The structure soln. and refinement followed std. procedures, in which all H atoms were treated without constraints. The mols. have a synclinal conformation (torsion angle O1-Cl-C2-O2 -64.4 Deg) and the packing consists of catamer-like, two-dimensional networks with H bridges parallel to the  plane, O...O distances 2.711(1) and 2.730(2) .ANG. and O-H...O angles 176(2), 171(2) Deg.