Synthesized, isolated, and characterized by X-ray crystallography and NMR spectroscopic studies, lithium phosphidoaluminate iBu3AlPPh2Li(THF)3 has been tested as a catalyst for hydrophosphination of alkynes, alkenes, and carbodiimides. Based on the collective evidence of stoichiometric reactions, NMR monitoring studies, kinetic analysis, and DFT calculations, a mechanism involving deprotonation, alkyne insertion and protonolysis is proposed for the [iBu3AlHLi]2 aluminate-catalyzed hydrophosphination of alkynes with diphenylphosphine. This study enhances further the development of transition metal free, atom economical homogeneous catalysis using common sustainable main group metals