A novel interface to InSb based on photochemical native oxide (PNOX), which improves conventional ultraviolet (UV) enhanced deposition, is reported. Prior to the deposition of SiO2, an additional stage of growing a native oxide by exposing the semiconductor to N2O and Hg vapors at low pressure under UV illumination is introduced. Composition and electrical properties of the interface are discussed. Compositional analysis was performed by Auger electron spectroscopy. Electrical properties were characterized using metal-insulator semiconductor (MIS) capacitors and photodiodes implemented with UV enhanced chemical vapor deposition (CVD) oxide/PNOX/InSb. Interface state densities of 2-4×1011 cm-2 eV-1 are obtained with good uniformity and stability. The hysteresis of the MIS structure with 1000 Å photoinduced CVD oxide on PNOX is very small, about 0.32 V for a ±20 V span measured at 77 K.