The crystal and molecular structures of Ru4(µ-H)4(CO)11(CNBut) (2), obtained with Ru4(µ- H)4(CO)10(CNBut)2 by hydrogenation of Ru5(µ5-CNBut)(CO)14(CNBut) (1), have been determined. Crystals of (2) are monoclinic, space group P 21/c, with a 12·349(1), b 11·627(3), c 17·0222(7) Å, β 105·785(4)°, V 2351·9(6) Å3 and Z 4. The structure was solved by direct methods and refined using 4478 reflections to final R 0·028(Rw0·033). An improved procedure for the preparation of (1) in 35–40% yields is also described.