The performance of the direct carbon solid oxide fuel cell (DC-SOFC) with various solid oxide electrolytes: 8 mol% Y(2)O(3) in ZrO(2) (8YSZ), 9 mol% Sc(2)O(3) in ZrO(2) (9ScSZ) and 10 mol% Gd(2)O(3) in CeO(2) (20GDC) were examined in temperature range 600-880 degrees C. The highest current densities were obtained for DC-SOFC with 20GDC electrolyte. It was shown that the DC-SOFC performance improved when thickness of the electrolyte was reduced, which can be attributed to the decrease of ohmic polarisation. The performance of DC-SOFC was also improved for a composite fuel consisted of powdered carbon fuel and 8YSZ or 20GDC ionic oxide electrolyte in the amount of ca. 10 wt.%. Catalytic effects of Ag and Ni particles addition to the carbon fuel on the DC-SOFC operation were also investigated. (C) 2010 Elsevier B.V. All rights reserved.