由於8%YZOI • Zr02(YSZ)具有導氧之性質，以CU/CU20粉末做為參考點，利用外載式高 溫參考電極量測外部水質pH改變。在實驗室高溫高壓系統中，利用YSZ和Pt電極量測九種溶耀在2S0·C' 270·C和300·C 下之pH值，並與理論MULTEQ軟體計算之pH值做比較。結果顯示YSZ電極對大部分的溶被可提供可靠之pH量測，且YSZ和Pt所量測之電位比較，呈現線性關係，意即YSZ電極之反應符合可逆之Nernstian關係。

The high temperature pH monitor is set up by filling the 8% Y 203 Zr02(YSZ) tube with the CU/CU20 powder which acts as a reference point. Due to the oxygen conducting property of YSZ in high temperature environment， the pH value can be obtained by measuring the potential dilTerence across the YSZ wall. In laboratory testing system， the pH values of 9 different solutions have been measured at temperature of 250·C， 275·C and 300·C by using YSZ and Pt electrodes. The results have also been compared with the theoretical values calculated by MUL TEQ program. Itshows the YSZ electrode can offer reliable pH measurement in high temperature aqueous environment.