The title complex, [Mo(C24H30N2P2)(CO)4], contains a molybdenum centre bearing a P,P′-cis-chelating Ph2PN(iPr)P(Ph)NH(iPr) and four carbonyl ligands in a distorted octa­hedral coordination geometry. This results in a nearly planar four-membered metallacycle. In the crystal, mol­ecules are linked by N—H...O and C—H...O hydrogen bonds to form layers parallel to the ac plane. For the final refinement, the contributions of disordered solvent mol­ecules were removed from the diffraction data with SQUEEZE in PLATON [Spek (2015). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown solvent mol­ecule(s).