The formation of anodic fluoride on HgMnTe has been studied and the composition of the interface and the chemical depth profiles have been characterized by x-ray photoelectron spectroscopy technique. Comparison results between HgMnTe and HgCdTe were given. Metal-insulator-semiconductor devices containing an anodic fluoride layer and a ZnS coating were fabricated and characterized. The mixture of anodic fluoride and thin native oxide layer may create a good interface for HgMnTe passivation.