The electrical conductivity and the activation energy of conduction were measured up to 340degreesC for undoped sulfur melts and doped sulfur melts with 5 mol% LiF, 5 mol% NaF, 13.4 mol% NaCl, 1 and 5 mol% KCl, 5 mol% NaBr, 5 mol% Se, 5 mol% NaBr + 5 mol% Se, 5 mol% Na2SO4, 5 and 10 mol% Na. The effect of irradiation of ultrasonic waves of 20 kHz was studied. The electrical conductivity generally increased with increasing temperature above 200degreesC with a variety of temperature dependencies. The addition of NaBr, Se, LiF, Na2SO4, NaBr + Se, and KCl caused an increase in conductivity in this order by max. two orders of magnitude For sulfur melts doped with 5 and 10 mol% Na, a wide jump of electrical conductivity occurred at 245degreesC, giving exceedingly high electrical conductivities above this temperature. By the irradiation of ultrasonic waves, the electrical conductivity was raised together with the formation of jump for Se, NaBr + Se, 5 mol% Na, LiF, Na2SO4, NaBr and NaF The largest irradiation effect was observed for 10 mol% Na, for which the jump temperature was 190degreesC The activation energies classified into low, medium, and high groups were obtained. The assumption of microscopic temperature was proposed, which was found to explain the electrical conductivity of irradiated melts.