Abstract: The mixed oxides Pr_2-xSr_xCoO_4±λ(0.2≤_x≤1.0) with K₂NiF₄ structure were synthesized by the polyglycol gel method.The composition and structure of the catalysts were characterized by means of XRD,TPD,TPR,XPS,and chemical analysis.The catalytic performance for CO and C₃H₈ oxidation was investigated.The results showed that the mixed oxides displayed K2NiF4 structure.Other phases were found when x=0.2 and x=1.0 and the mixed oxide was single A₂BO₄ when 0.2<x<1.0.With the increase of x, average crystalline size, unit cell volume and lattice parameters of Pr_2-xSr_xCoO_4±λ catalysts decreased gradually, however, the concentration of oxygen vacancy, the desorption amount of lattice oxygen, the amount of Co³⁺, and lattice distortion increased gradually.There were only the desorption peak approaching BE (529 eV) in the O1s curves of Pr_2-xSr_xCoO_4±λ catalysts when x=0.2 and x=0.4.However, the O_1s curves of Pr_2-xSr_xCoO_4±λ catalysts, when x=0.6—1.0,included two peaks, and the peak areas approaching BE (531 eV) increased with the increase of x.The catalytic activities for CO and C₃H₈ oxidation were closely correlated with oxygen vacancy, lattice oxygen and Co³⁺.