The oxygen nonstoichiometry of (La,Sr)(Co,Cu)O3-delta(LSCC) was measured thermogravimetrically. It was found that LSCC has no oxygen excess region. Its behavior is similar to (La,Sr)FeO3-delta(LSF) but not to (La,Sr)MnO3+/-delta(LSM). The electrical conductivity decreases as compared to (La,Sr)CoO3-delta(LSC). However, it was expected that the ionic conductivity in LSCC would increase, as is suggested from electrical conductivity measurement and oxygen nonstoichiometry measurements. High temperature XRD analysis showed the elimination of phase transformations by addition of Cu yet with no reduction in the thermal expansion coefficient. The cathode activity of LSCC, the electrode interfacial conductivity, sigma(E), was 15.32 S cm(-2) in air at 1073 K. The electrode activity of LSCC is better than that of LSC, although the electrical conductivity of LSCC is lower.