Three kinds of carbon sources obtained from carbon black, bamboo fiber and waste paper were investigated as anode fuels in an intermediate temperature direct carbon fuel cell. The carbon sources were characterized with X-ray photoelectron spectroscopy, thermal gravimetric analysis, etc. The results indicated that the waste paper carbon was more abundant in calcite and kaolinite, and showed higher thermal reactivity in the intermediate temperature range compared with the other two carbon sources. The cell performance was tested at 650 degrees C in a hybrid single cell, using Sm0.20Ce0.80O2-x as the electrolyte. As a result, the cell fed with waste paper carbon showed the highest performance among the three carbon sources, with a peak power density of 225 mW cm(-2). The results indicated that its inherent impurities, such as calcite and kaolinite, might favor the thermal gasification of renewable carbon sources, which resulted in the enhanced performance of the intermediate temperature direct carbon fuel cell. (C) 2014 Elsevier Ltd. All rights reserved.