Effective hydrogenolysis of dimethyl oxalate to ethylene glycol has been obtained using a catalyst prepared in situ from Ru(acac)(3) with the facially coordinating tridentate phosphine ligand CH3C(CH2PPh2)(3). This catalyst enabled full and selective conversion in 16 h at [S]/[Ru] = 500 at 80-100 bar hydrogen pressure at 120 degreesC. This catalyst is far more active than any known homogeneous catalyst able to hydrogenate dimethyl oxalate to ethylene glycol. Several mono-, di- and tridentate P- and N-ligands have been selected and were evaluated, several of which showed (almost) no reactivity. In some cases, for instance when using the meridional coordinating ligand PhP(C2H4PPh2)(2), selectivity can be directed toward the semi-hydrogenolysis product methyl glycolate. (C) 2003 Elsevier B.V. All rights reserved.