Stability of p-type transparent conducting oxides, CuAlO2, CuGaO2 and SrCu2O2, at high temperature has been studied by thermogravimetry, X-ray diffraction and thermodynamic calculation. It has been revealed that they decompose at high temperature in air according to the following chemical reaction formula; 4CuMO2 ＋O2 → 2CuO＋2CuM2O4 (M = Al, Ga) and 28SrCu2O2 ＋17O2 → 2Sr14Cu24O41 ＋8CuO. Assuming the first order reaction, kinetics of the chemical reactions and their activation energies have been evaluated from weight variation by time at the constant temperature measured by thermogravimetry. It was concluded that the order of the kinetic stability was CuAlO2, CuGaO2 and SrCu2O2. Ellingham diagram of the chemical reactions prepared in this study showed that thermodynamic stability of CuAlO2 was higher than that of CuGaO2 and SrCu2O2. It was also revealed that CuAlO2, CuGaO2 and SrCu2O2 are not thermodynamically stable in air below 800 ℃, 1200 ℃ and 1140 ℃, respectively, showing agreement with the weight increase due to the chemical reactions at constant temperatures in air. It can be expected that the p-type transparent conducting oxides would be kinetically stable with decreasing oxygen partial pressure, since temperatures where CuAlO2, CuGaO2 and SrCu2O2 decomposed decreased in the Ellingham diagram. However, decomposition of SrCu2O2 was observed even at 400 ℃ under oxygen partial pressure of 10 －3 atm, which could be attributed to fast kinetics of the reaction even at 400 ℃ under such a low oxygen partial pressure.