The diphosphane-substituted clusters [Ru-3(CO)(10)(dppe)] and [Ru-3(CO)(8)(dppe)(2)] [dppe = 1,2-bis(diphenylphosphanyl)ethane] are shown to catalytically hydrogenate diphenylacetylene. This process is highly solvent-dependent with fragmentation dominating in low-polarity solvents, which indicates that the dppe ligand does not stabilise the cluster under catalytic conditions. In solvents of higher polarity, the clusters are active hydrogenation catalysts of lower activity than their monodentate phosphane analogues [Ru-3(CO)(10)(L)(2)] (L PPh3, PMe2Ph, PMe3, PCy3). ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).