SmBaCo(0.5)Mn(1.5)O(5+delta )oxide with Sm-Ba cation-ordered perovskite-type structure is synthesized and examined in relation to whole RBaCo(0.5)Mn(1.5)O(5+delta )series (R: selected rare earth elements). Presence of Sm and 3:1 ratio of Mn to Co allows to balance physicochemical properties of the composition, with moderate thermal expansion coefficient value of 18.70(1).10(-6) K-1 in 300-900 degrees C range, high concentration of disordered oxygen vacancies in 600-900 degrees C range (delta = 0.16 at 900 degrees C), and good transport properties with electrical conductivity reaching 33 S cm(-1) at 900 degrees C in air. Consequently, the compound enables to manufacture catalytically-active cathode, with good electrochemical performance measured for the electrolyte-supported laboratory-scale solid oxide fuel cell with Ni-Gd1.9Ce0.1O2-delta vertical bar La0.4Ce0.6O2-delta vertical bar La0.8Sr0.2Ga0.8Mg0.2O3-delta vertical bar SmBaCo0.5Mn1.5O5+delta configuration, for which 1060 mW cm(-2) power density is observed at 900 degrees C. Furthermore, the tested symmetrical SmBaCo0.5Mn1.5O5+delta vertical bar La0.8Sr0.2Ga0.8Mg0.2O3-delta vertical bar SmBaCo0.5Mn1.5O5+delta cell delivers 377 mW cm(-2) power density at 850 degrees C, which is a promising result. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.