In toluene solution, the reaction of [Co2(CO)8] with an equimolar amount of [P(OPh)3] yields first [Co2(CO)7{P(OPh)3}] 1. Following heating of 1, an alternative synthetic access to the tetranuclear cluster [{Co4(μ2-CO)3(CO)8{P(OPh)3}] 2 is provided in a condensation reaction. Compound 2 has been characterized by IR and 31P NMR spectroscopy. The tetranuclear cluster framework has been ascertained by a single-crystal X-ray diffraction study performed at 100 K.