For application in high temperature fuel cells and oxygen sensors, alkaline earth doped lanthanoide manganites have been studied systematically with regard to preparation conditions, structures, electrical conductivities and thermal expansion coefficients, respectively. La1-xSr(Ca)xMnO3, (x=0-0.5) show a cubic perovskite structure for Ca-containing at x= 0.2-0.5 and for Sr-containing at x=0.5. For Gd(Nd)1-xCaxMnO3 (x=0-0.5) an orthorhombic distorted perovskite structure was found. Yb(Y)1-xCaxMnO3 shows in the range of x=0.3-0.5 an orthorhombic structure, whereas for the pure Yb(Y)MnO3 the hexagonal structure was determined. A correlation between the conductivity of doped lanthanum manganites and the concentration of Mn" could be found. The suitability of these materials as an electrode for zirconia cells has also been studied in detail. At temperatures under 1073 K the polarization resistivity of the best electrodes based upon La0.7Ca0.3MnO3 is much smaller than such made of active platinum. Electrodes were tested in solid electrolyte fuel cells.