The crystal structure at room temperature, and the thermal expansion and electrical conductivity, from room temperature up to 800 degrees C, of the perovskite-type oxides in the system Pr(1-x)Sr(x)CoO3-delta (x = 0, 0.15, 0.3, 0.4, 0.5) were studied. All compounds have the orthorhombic perovskite GdFeO3-type structure (Pbnm space group). The lattice parameters were determined by X-ray powder diffraction. The introduction of Sr2+ into the lattice is compensated by the oxidation of Co3+ to form Co4+ (holes) for low x, and at reduced temperatures on higher x values, or by the formation of oxygen vacancies as x increases and at high temperatures. Above x = 0.4 oxygen vacancies are formed even at room temperature. The thermal expansion is almost linear for x greater than or equal to 0.15. The thermal expansion coefficient (TEC), determined in the temperature range from room temperature to 500 degrees C, decreases with x, but shows an increase above x = 0.4. The electrical conductivity increases with x, but when x greater than or equal to 0.4 it decreases. The conductivity of the undoped sample in the examined temperature range, and that of x = 0.15 up to 500 degrees C is p-type semiconducting, and can be described by the small polaron hopping mechanism. Semi-metallic behavior was observed for x = 0.15 above 500 degrees C and for x greater than or equal to 0.3 in the whole examined temperature range. The metal-insulator (M-I) transition at room temperature occurs at approximately x = 0.25.