A three-dimensional X-ray crystal structure analysis of the compound Na(PhCO·CH·CO·Me)(HOCH2·CH2OH) has been carried out. Preliminary results were obtained photographically and the structure was solved by direct methods. Final results are derived from 1145 observations made with a diffractometer. The crystals are triclinic with a= 12·19, b= 7·665, c= 7·26 Å, α= 113·0, β= 83·1, γ= 87·5°, space group P, and Z= 2. R= 0·059 with isotropic vibration parameters for the hydrogen atoms and anisotropic vibration parameters for the other atoms. The structure consists of a polymeric chain, parallel to the a-axis, held at alternate centres of symmetry by [graphic omitted] bridges, formed by sharing an oxygen atom of the β-diketone, and at the other centres by bridges formed by two glycol molecules. Hydrogen bonding reinforces the latter bridges. Parallel to (100) the packing is between phenyl and methyl groups. The sodium is 0·65 Å from the base of a tetragonal pyramid of oxygen atoms (Na–O 2·286–2·361 Å) the apex of which is one oxygen atom from a glycol molecule. Bond lengths in the phenyl ring and in the β-diketone ring are normal, the angle between the planes of these two rings is 34°.