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