Abstract: Oxygen permeability of dense perovskite-type Y1−x La x Ba2Cu3O7−δ (x =0.1, 0.3, 0.5, 0.8 and 1.0) and Y1−y Ca y Ba2Cu3O7−δ (y =0.1, 0.2, 0.3 and 0.4) membranes were investigated under an air/He gradient in a temperature range from 750 to 950°C. The results indicate that doping of La or Ca has great effects on the oxygen permeability. Oxygen permeation flux of Y1−x M x Ba2Cu3O7−δ (M=La, Ca) membrane increases with M substitution for Y in YBa2Cu3O7−δ , and has an obvious increase at about 900°C due to an order–disorder transition of the oxygen vacancies in the membrane material. Maximum oxygen fluxes of 0.92 and 0.77μmol/scm2 are obtained for LaBa2Cu3O7−δ (x =1.0) and Y0.8Ca0.2Ba2Cu3O7−δ (y =0.2) membranes with thickness 1.0mm at 950°C, respectively. [Copyright &y& Elsevier]