Changes of the relative mass and heat absorption-heat evolution of palladium were measured by TG and DSC in a temperature rising process from room temperature to 1200 oC. The surface chemical species of palladium samples with different treatment systems were determined by XPS. For sponge palladium, a series of thermal effects, such as the formation, decomposition and evaporation of PdO at 260, 720 and 877 oC, respectively were observed on the heat absorption-heat evolution curves. The oxidation of palladium is a mass-gain process below 750 oC, and the decomposition and evaporation of PdO lead to mass loss at temperatures above 750 oC. When heated or quenched above 850 oC, Pd presents Pdo state and keep a bright metallic surface; while heated or quenched below 850 oC, Pd is coated by PdO and thus exhibits a dull color