High-temperature X-ray diffraction revealed peculiarities of thermal expansion of Sr3YCo4O10.5 with tetragonal 314-structure such as anisotropy of the lattice expansion (thermal expansion coefficient of the a-parameter TECav(a) = 18.6 ppm K-1, TEC(c) = 25.6 ppm K-1) and two intermediate regions with different TEC anisotropy: TEC(c)/TEC(a)= 1.98 at 298-773 K and 0.96 at 773-1173 K. Replacement of Co by Fe in Sr3YCo4-xFexO10.5 + y leads to decreasing of TEC at T < 673 K to 16.6 ppm K-1 for x = 1.0 and 14.6 ppm K-1 for x = 3.0. At T > 673 K increase of TEC up to similar to 20 ppm K-1 due to the oxygen loss from the crystal structure is observed. Sr3YCo4-xFexO10.5 + y compounds show high electrical conductivity values at 1173 K up to similar to 200 S/cm for Sr3YCo4O10.5. A decrease in conductivity at high temperature is observed with increasing the Fe-content. (c) 2008 Elsevier B.V. All rights reserved.