Internally oxidized iron alloys and α-Fe were deformed at 650∼850°C. And some activation parameters were obtained. Stress exponents, apparent activation energies and activation volumes were similar to those of α-Fe. High temperature deformation of these alloys is controlled by lattice diffusion. In these alloys, the average internal stresses were slightly higher than in α-Fe. The effective stress exponent of the average dislocation velocity was 2∼3 and had slight temperature dependence.