Cyclopentadienyluranium(IV) acetylacetonate complexes, ( η 5C 5H 5)UCl 3− x (acac) x , where x = 1 or 2, and the corresponding bis triphenylphosphine oxide (tppo) complexes have been prepared. The bis cyclopentadienyl complexes, ( η 5C 5H 5) 2U(acac) 2 and ( η 5C 5H 5) 2UCl(acac)(tppo) 2 have also been prepared and are stable with respect to disproportionation, whereas ( η 5C 5H 5) 2UCl(acac) is not. The IR and UV/visible spectra of the complexes are reported, together with some additional information on the UCl 2(acac) 2thf and -tppo systems.