One major problem in the power output of alkali metal thermal to electric converter (AMTEC) is its decay with time. From the 18,000 h of laboratory testing on AMTEC, it was found that power output decreased from 2.48 to 1.27 W. One of the major causes of this decay is the growth of the electrodes. In this study, three electrodes have been studied in terms of their grain growth and a comparison of their performance has been made. Materials for those three electrodes, namely, RhW, Rh2W, and TiN have been tried. From this analysis, RhW was found to be the best electrode, whereas Rh2W was found to be the better electrode over TiN electrode. It was observed that power degradation of RhW electrode is 3.63% from grain growth effect. Power degradation by Rh2W and TiN electrodes were calculated to be 6.45 and 10.89%, respectively, due to grain growth.