Flexible thermoelectric power generators fabricated by evaporating thin films on flexible fiber substrates are demonstrated to be feasible candidates for waste heat recovery. An open circuit voltage of 19.6 mu V K per thermocouple junction is measured for Ni-Ag thin films, and a maximum power of 2 nW for 7 couples at Delta T = 6.6 K is measured. Heat transfer analysis is used to project performance for several other material systems, with a predicted power output of 1 mu W per couple for Bi2Te3/Sb2Te3-based fiber coatings with a hot junction temperature of 100 degrees C. Considering the performance of woven thermoelectric cloths or fiber composites, relevant properties and dimensions of individual thermoelectric fibers are optimized. (C) 2007 Published by Elsevier B.V.