The present paper is concerned with determination of the three characteristic functions involved in the authors' theory on the plastic deformation of metals at high temperatures, being derived from the results of constant strain rate tension tests and constant stress creep tests. Tests were made with 0.14 percent carbon steel at a temperature of 450°C. The functions determined from the results or tension tests were in good agreement with those from the results of creep tests. Therefore, it is concluded that the results of the tension test are related with those of the creep test through the three characteristic functions in the authors' theory.