When KMnO4 is γ irradiated at 77°K a single paramagnetic species is detected which is shown to be basically the manganate ion, Mn(VI)O42−, however, the single odd electron interacts at the same time with a second manganese nucleus of a neighboring diamagnetic species. Although the species giving rise to the weaker, superhyperfine 55Mn interaction could not be identified with certainty, it is probably a neighboring MnO4− ion or MnO3+ lattice defect so that the center produced might be written [Mn(VI)O42−··· Mn(VII)On7−2n]. The g tensor and both 55Mn hyperfine splitting tensors have been obtained, and the structure of the radical is discussed. On warming to room temperature a radical not containing manganese, probably O3−, is found.