In this study, the effects of hydrazine treatment on the surface of H-CdTe were investigated by X-ray photoelectron spectropscopy (XPS) and metal-insulator-semi conductor (MIS) capacitance-voltage (C-V) analyses. By the XPS analysis, it was found that the Te4+ oxide peak at 576.2eV disappeared clearly from the surface of HgCdTe after hydrazine treatment. The hydrazine-treated sample showed a near-flatband condition, small hysteresis, and a high-frequency characteristic in C-V measurements. The photodiodes fabricated on hydrazine-treated HgCdTe showed dynamic resistance-area product values at zero bias (R(0)A) of similar to 2.54 Omega cm(2) for a junction area of 30 x 30 mu m(2), which are about ten times larger than those on Br-treated HgCdTe.