The ac conductivity measurements have been carried out for the activated Ba/SrO cathode with additional 5% Ni powder for every 100 h acceleration life time at the temperature around 1125 K. The ac conductivity was studied as a function of temperature in the range 300-1200 K after conversion and activation of the cathode at 1200 K for 1 h in two cathodes face to face closed configuration. The experimental results prove that the hopping conductivity dominate in the temperature range 625770 K through the traps of the WO3 associate with activation energy E-a = 0.87 eV, whereas from 500-625 K it is most likely to be through the traps of the Al2O3 with activation energy of E-a = 1.05 eV. The hopping conductivity at the low temperature range 300-500 K is based on Ni powder link with some Ba contaminants in the oxide layer stricture which indicates very low activation energy E-a = 0.06 eV (c) 2005 Elsevier B.V. All rights reserved.