In the present work, we investigated potential means to obtain neutral tricarbonyl mixed-ligand fac-[M(CO)LL] complexes (M = Re, Tc) containing the (2-hydroxyphenyl)diphenylphosphine (POH) bidentate ligand (LH) and a series of monodentate ligands (L). First, fac-[Re(CO)(PO)(HO)], 1, was synthesized by reaction of POH and [EtN][Re(CO)Br] in equimolar amounts in MeOH at room temperature. Interestingly, with excess of POH this reaction afforded fac-[Re(CO)(PO)(POH)], 2, with POH operating both as a bidentate and as a monodentate ligand. Owing to the presence of the labile aqua ligand, which can be readily replaced by various monodentate ligands, 1 was further used as a precursor to generate a small library of the desired fac-[M(CO)LL] complexes. Specifically, by reaction of triphenylphosphine (PPh), imidazole (im), pyridine (py), cyclohexyl isocyanide (cisc), and tert-butyl isocyanide (tbi), the following products were readily obtained in excellent yields (92%-95%): fac-[Re(CO)(PO)(PPh)], 3, fac-[Re(CO)(PO)(im)], 4, fac-[Re(CO)(PO)(py)], 5, fac-[Re(CO)(PO)(cisc)], 6, and fac-[Re(CO)(PO)(tbi)], 7. All compounds were fully characterized by elemental analysis, IR and NMR spectroscopies, and electrospray ionization(+) mass spectrometry. Their solid-state structure was elucidated by X-ray crystallography. Of considerable interest is the fact that the corresponding 2'-7' were easily accessible at the Tc-tracer level in quantitative yields after reaction of POH and the respective monodentate ligand L with fac-[Tc(CO)(HO)] in aqueous MeOH, as verified by comparative chromatographic methods adopting dual photo- and radiometric detection modes. The high stability displayed by all Tc complexes during histidine and cysteine challenge assays underscored the suitability of the fac-[M(CO)(PO)L] system for radiopharmaceutical development purposes.