Recently, there is a strong interest in developing superior thermoelectric devices and materials. The performance of a thermocouple can be considerably improved by applying a gradient of composition along the temperature gradient inside the thermocouple causing that at each position the respective material achieves its maximum thermoelectric efficiency (TE FGM principle). Combining the thermoelectric materials Bi2Te3 (used at low temperatures) and FeSi2 (applied up to high temperatures) will result in a thermoelectric device operating at a wide temperature range. The challenge is to contact these dissimilar materials without any negative impact on the thermoelectric properties. Besides providing good electrical and thermal contact of Bi2Te3 and FeSi2 the junctions have to be mechanically and chemically stable. In order to maintain mechanical stability an interlayer adjusting the different coefficient of thermal expansion alpha of FeSi2 (10.10(-6) K-1) and Bi2Te3 (19.10(-6) K-1) is essential. Various composites of Bi2Te3-SiO2 approximating alpha of FeSi2 have been employed as connecting layer. The contacts between those and Bi2Te3 and FeSi2, respectively, were prepared by uniaxial hot pressing. While the mechanical stability is enhanced significantly by a Bi2Te3-SiO2 composite, the thermoelectric conversion efficiency of the FGM decreases. Therefore the thermoelectric properties of the FGM material were studied regarding the ratio Of SiO2 in the composite. In addition the diffusion of FeSi2 and Bi2Te3 near the interface of the Bi2Te3-SiO2 composite, the mechanical stability, and the microstructure of the FGM were studied.