From the reaction of [Rh(Q)(1,5-cod)] (HQ=1-phenyl-3-methyl-4-R-pyrazol-5-one: R=2-thenoyl (HQ S) or 2-furanoyl (HQ O)) with PPh 3, 1,2-bis(diphenylphosphino)ethane (dppe) or 1,3-bis(diphenylphosphino)propane (dppp) in anhydrous solvents under N 2 the complexes [Rh(Q)(PPh 3) 2], [Rh(dppe) 2](Q) (Q=Q S or Q O), and [Rh(dppp)(Q O)] were obtained. The reactions of [Rh(Q S)(1,5-cod)] with CH 3I, I 2, HCl and C 3H 5Br in the presence of PPh 3 were also investigated. All compounds obtained were characterized by elemental analyses, FT-IR, ESI-MS spectroscopy, 1H-, 31P- and in selected cases by 13C-NMR spectroscopy. [Rh(Q S)(PPh 3) 2], [Rh(dppe) 2](Q S), [Rh(Q O)(dppp)] and [Rh(Q S)Cl 2(PPh 3) 2], were also characterized in the solid state by single crystal X-ray diffraction. In the air oxidation of [Rh(Q)(PR 3) 2] and [Rh(Q O)(dppp)] occurred, species containing a η 2-peroxo group being always identified.