In this study, effects of thermal treatment conditions on the capacitive deionization performance (CDI) of activated carbon cloth (ACC) electrodes have been investigated. A total of 8 different treatment conditions has been studied by systematically changing the type of gas (Ar, CO2, N-2) and the treatment temperature (700, 800, 850 degrees C). Treated electrodes were subjected to electrochemical testing and morphological analysis in order to assess the changes in the CDI performance. Results indicated a major discrepancy between the electrochemical and the CDI performance of the treated electrodes depending on the treatment condition. For instance, electrochemical testing showed 15% improvement in charge storage for N-2-treated electrodes, while CDI performance was found to decrease by 20%. On the other hand, improvements in both electrochemical (25%) and CDI performances (60%) were observed for Ar and CO2 treated electrodes. These findings indicate that different treatment conditions promote distinct charge compensation mechanisms at the electrode surface; some of which are not beneficial for salt adsorption. Moreover, results highlight the significance of selecting a suitable thermal treatment condition for achieving enhanced performance in CDI systems utilizing ACC electrodes.