A series of 1 ∶ 1 adducts of B(C₆F₅)₃ with the organophosphoryl ligands Et₃PO, Ph₃PO, Prⁿ ₃PO, Octⁿ ₃PO, (MeO)₃PO, (EtO)₃PO, (PhO)₃PO, (EtO)₂(H)PO, (BuⁿO)₂(H)PO, (PhO)₂(H)PO, (MeO)₂MePO, (EtO)₂MePO, (EtO)₂PhPO, and (EtO)Me₂PO have been synthesized and characterised by elemental analysis, mp, and spectroscopic (¹H, ¹³C, ¹¹B, ¹⁹F, ³¹P NMR and IR) methods. B(C₆F₅)₃·Ph₃PO was further characterised in the solid state by a single-crystal X-ray diffraction study. ³¹P NMR chemical shifts and ν(PO) IR stretching frequencies are discussed in relation to substituent at phosphorus.