An experimental setup for determining the electrical resistivity of several types of thermoelectric materials over the temperature range 20 < T < 550 °C is described in detail. One resistivity measurement during temperature cycling is performed and explained for Cu(0.01)Bi(2)Te(2.7)Se(0.3) and a second measurement is made on Yb(0.35)Co(4)Sb(12) as a function of time at 400 °C. Both measurements confirm that the materials are thermally stable for the temperature range and time period measured. Measurements made during temperature cycling show an irreversible decrease in the electrical resistivity of Cu(0.01)Bi(2)Te(2.7)Se(0.3) when the measuring temperature exceeds the maximum sample fabrication temperature. Several other possible uses of such a system include but are not limited to studying the effects of annealing and/or oxidation as a function of both temperature and time.