Yttrium aluminum carbide (YAl3C3) was investigated by density functional theory (DFT) calculations and Cu K alpha(1) X-ray powder diffraction analysis to clarify the electronic and structural features responsible for its thermoelectric properties. The experimental electron density distribution from the X-ray data was consistent with the valence electron density distribution from DFT calculations. A narrow band gap was obtained in calculated density of states, which suggested a poor metallic or semi-metallic behavior. Electron density of the lowest unoccupied molecular orbitals indicated that the YAl3C3 has a nanolaminate structure along the c axis, which comprises two-dimensional electrically conductive Y and more insulating Al-C layers. (C) 2007 Elsevier B.V. All rights reserved.