Synchrotron radiation photoemission spectroscopy has been used to study the formation of the reactive V/GaAs(110) interface. Valence-band and core-level results indicate that metal deposition produces an extended intermixed phase involving the formation of both V–Ga and V–As bonds. In this reacted region the Ga 3d core line exhibits a continuous shift to lower binding energy (total shift 1.55 eV over band bending) indicative of a variable chemical environment, while analysis of the As 3d line shape suggests that As is present in two well-defined chemical states. Core-level intensity profiles show preferential outdiffusion of arsenic, with As present at ∼6% of the original level with coverages of 110 Å. Comparison to previous results for Cr/GaAs(110) shows similar Ga and As attenuation profiles.