Using the differential pusle polagraphy, the values of the hafe wave potential (E,1/2,) of the new radiosensitizer CM, Misonidazole MISO and Metronidazole were measured, and also compared under the same condition. The results showed that the magnitude of the E,1/2, Was as follows; MISO,>,CM,>,Metronidazole. The data demonstrates that their reduction ability correlates well with their radiosensitization. Although the electronaffinic potency of CM and its radiosensitization in vitro are in the middle, CM has properties of tumor-affinity to a certain extent. low toxicity and high therapeutic index, and the preliminary clinical results indicate that CM is a low toxic and efficient radiosensitizer.