Gold-phosphido-monolayer-protected clusters (MPCs) of 1-2-nm diameter, Au-x(PR2)(y), analogues of the well-known thiolate materials Au-x(SR)(y), were prepared by NaBH4 reduction of a mixture of HAuCl4.3H(2)O and a secondary phosphine PHR2 in tetrahydrofuran/water. In comparison to the Au-thiolate MPCs, fewer of the larger phosphido groups are required to cover the surface, and the Au-P bond is not cleaved as readily in reactions with small molecules as is its Au-S counterpart. P-31 NMR spectroscopy provides a direct method to study cluster formation and the interaction of the phosphido ligand with the gold surface.