A copper-doped ferrite with the chemical composition La0.7Sr0.3Cu0.2Fe0.8O3-delta (LaSrCuFe) was prepared using the classical ceramics method starting from the oxides. The linear thermal expansion coefficient in air was measured in the temperature range between 550 and 1,250 K to be between 10 x 10(-6) and 15 x 10(-6) K-1. The electrical conductivity in air was found to be higher than 100 S cm(-1) for temperatures lower than 1,100 K. A change of oxygen stoichiometry was found above 650 K in an atmosphere of 20 vol% oxygen with argon. This change can be correlated with the electrical conductivity.