We present details of the interfacial chemical reactions and intermixing observed for Cu,Ag, and Au overlayers on the clean cleaved InP(110) surface using soft x‐ray photoemissionspectroscopy (SXPS). Analysis of the P 2p and In 4d core levels and the P L V V Auger line reveals a range of chemical interactions: Cu–P metallic bonding with phase segregation of metallic In for Cu overlayers, Ag islanding with a small amount of In segregation for Ag overlayers, and elemental P precipitation with Au–In alloying for Au overlayers. Deconvolution of the substrate and reacted layer components of the core level spectra is used to determine the Fermi level pinning positions for Ag and Au on n‐ and p‐type InP, and these values are compared to theoretical calculations of native defect energy levels.