RuO2/YSZ (8% Y2O3 stabilized ZrO2)-based material was evaluated for SOFC cathodes. Subsolidus phase equilibria in the binary RuO2-ZrO2 system and ternary RuO2-ZrO2-y2O3 system were studied. No binary compound or solid solution exists between RuO2 and ZrO2, Which indicates the stability of the electrical and microstructural characteristics at "working" temperatures of SOFCs. Thick film electrodes, printed and fired on YSZ electrolyte, exhibited usable characteristics, i.e. a porous microstructure, good adhesion and compatibility with the YSZ substrate, low sheet resistivity and a positive temperature coefficient of resistivity.