A series of alkyldiphenylphosphines with straight-chain alkyl groups, PPh2(CnH2n+1), where n = 5–20, their oxides, P{O}Ph2(CnH2n+1), and sulfides, P{S}Ph2(CnH2n+1), where n = 1–20, have been prepared. The tertiary phosphines are air sensitive and the lower members of the series (n < 9) are colourless, viscous liquids whereas the higher homologues are white waxy solids. The phosphine oxides and sulfides are air stable white crystalline solids. The alkyldiphenylphosphines were reacted with [PtCl2(COD)] (COD = 1,5-cyclooctadiene) to formcis-[PtCl2(PPh2CnH2n+1)2] complexes. All of the compounds were characterized by31P{1H} NMR spectroscopy. Mass spectrometry was further used to characterize all of the alkyldiphenylphosphines, their oxides, and sulfides, andcis-[PtCl2(PPh2CnH2n+1)2] complexes, where n = 1, 3, and 5.