A novel electrochemical approach based on voltammetric studies of reactions occurring at the HgCdTe/electrolyte interface has been devised to clean and reconstruct the HgCdTe surface prior to passivation. Sequential potential steps, applied to a HgCdTe specimen immersed in an electrolyte, oxidize the surface, remove Hg and leave a thin protective CdTe layer, reconstructed from the lattice atoms. A thick CdTe dielectric can be subsequently electrodeposited on this surface. The electrochemically processed interfaces were characterized by a low (1010cm−2 V−1) density of fast interface states, negligible concentration of slow traps and unusual stability to prolonged air exposure and to 100 °C air anneal. The electrochemical technique was further developed as a surface characterization tool to assess the quality of Br2‐etched HgCdTe surfaces. Monolayers of Te remaining on Br2‐etched surfaces convert sequentially to TeO2and then to HgTeO3on air exposure.