La2Ni0.5Cu0.5O4 and Pr2Ni0.5Cu0.5O4 Ruddlesden-Popper-type oxides were synthesized by a soft chemistry method and characterized in terms of their crystal structure as a function of temperature, thermal expansion coefficient, oxygen content, transport properties and chemical stability, as well as compatibility in relation to Ce0.8Gd0.2O1.9 electrolyte. La2Ni0.5Cu0.5O4 crystallizes in F4/mmm space group, while Pr2Ni(0.5)Cu(0.5)O(4) possesses Bmab symmetry. Oxygen nonstoichiometry was determined, showing oxygen excess at room temperature; La2Ni0.5Cu0.5O4.12 and Pr2Ni0.5Cu0.5O4.07, but with only small changes in air up to 850 degrees C. The obtained TECs are compatible to most commonly used electrolytes. Pr2Ni0.5Cu0.5O4 possesses relatively good electrical conductivity, exceeding 100 S cm(-1) in 300-800 degrees C. A maximum on the electrical conductivity, present for both materials, correlates well with minimum, observed on Seebeck coefficient characteristics. For Pr2Ni0.5Cu0.5O4-based SOFC, maximum power densities exceeding 0.13 W cm(-2) at 800 degrees C were recorded. Despite good performance, stability issues arise from a partial decomposition of the materials at 1000 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.