Introduction. As has been shown by Post, the total power required to produce a strong, steady-state magnetic field is strongly dependent upon the temperature at which the electrical conductor of the magnet operates. The power required for operation at very low temperature can, in some cases, be much less than that required for ambient temperature operation. The power required for low temperature operation depends on many system characteristics which include the metal chosen for the electrical conductor, the purity of this metal, and efficiency of the refrigeration equipment. This paper shows the relative power requirement, as a function of temperature, of a magnet with a particular shape and with a field strength of 100,000 gauss. Data is shown for three electrical conductors: copper, aluminum, and sodium.