The phase composition, linear thermal expansion coefficient, electroconductivity (in the temperature interval 600-900°C and partial pressures of oxygen 10^-5-0.21 atm) of solid-oxide materials based on gadolinium-barium cobaltite doped with 3d-elements BaGdCo_{2 - x} Me _x O_{5 + δ}, Me = Cu, Fe; x = 0.0, 0.2, ⋯, 2.0 were investigated. The homogeneity regions of samples were established by means of X-ray phase analysis. It was shown that the linear thermal expansion coefficient of cobaltite decreases with an increase in the copper or iron concentration. It was established that the electroconductivity of BaGdCo _{2 - x} Me _x O_{5 + δ} decreases with an increase in x. We concluded that upon a decrease in p(O₂), the electroconductivity of samples first decreases and then reaches a horizontal plateau.