AlN-SiC ceramics composed of AlN-SiC solid solutions were fabricated by pressureless sintering without sintering additives. The microstructure and electrical properties of the AlN-SiC ceramics were investigated for compositions between 0 and 75 mol% AlN. The AlN-SiC ceramics had a porous structure, and a 2H polytype was found in all compositions. The electrical conductivities and Seebeck coefficients of the AlN-SiC ceramics increased with temperature. The electrical conductivity of 25 mol% AlN-75 mol% SiC ceramics was the highest in all compositions: 32.7 S/m at 300 degrees C. In contrast, the electrical conductivity of 75 mol% AlN-25 mol% SiC ceramics was much lower than that of other samples: 10(-2) S/m at 300 degrees C. The Seebeck coefficient of 50 mol% AlN-50 mol% SiC ceramics was the highest of all samples: 210 mu V/K at 300 degrees C. The electrical and thermoelectrical properties of SiC can be controlled by the formation of AlN-SiC solid solutions.