Recently proposed thermoelectric applications of quantum dot superlattices made of different material systems depend crucially on the values of the electrical and thermal conductivities in these nanostructures. We report results of the measurements of Hall mobility and thermal conductivity in a set of Ge0.5Si0.5/Si quantum dot superlattices. The average measured in-plane Hall mobility for the undoped Ge/Si quantum dot superlattices on a p-type substrate is 233.5 cm(2) V-1 s(-1) at room temperature and 6.80 X 10(3) cm(2) V-1 s(-1) at 77 K. The average value of the thermal conductivity measured by 3ω method is about 10 W/mK at room temperature and 3.5 W/mK at 77 K. In the low-temperature region, the thermal conductivity is proportional to T-0.7 - T-0.9. Relatively large values of the carrier mobility and its temperature dependence suggest that the carrier transport in the investigated structures is likely of the band conduction type rather than hopping type. The thermal conductivity of the (GeSi0.5)-Si-0.5/Si quantum dot superlattices is strongly reduced and has its peak value shifted toward the high temperatures as compared to the constituent bulk materials. Obtained results can be used for GexSi1-x/Si quantum dot superlattice structure optimization for the high-temperature thermoelectric applications. © 2005 The Electrochemical Society. All rights reserved.