The electrical conductivity of two spinel peridotites from the Dreiser Weiher locality were investigated under defined oxygen fugacities at natural equilibrium pressure and temperature conditions. These rocks have the modal composition of spinel harzburgite (Ib/182) and spinel lherzolite (lb/8). The pyroxene solvus and the AI~O 3 content of the orthopyroxene have been used to estimate the p-T equilibration region of the selected nodules: T~, = 1164Β°C, and T8 = 1165Β°C, and P~82 = 18.5 kbar, andp8 = 19.8 kbar. The intrinsic oxygen fugacities of the nodules were determined experimentally by means of an electrical conductivity cell including a fayalite (Fe2SiO4) sensor. For the estimated equilibrium pressure and temperature conditions the measurements yielded log f(O2)=-10.1 to -9.7 (Ib/8), and log f(O2)=-7.5 to -7.1 (Ib/182), respectively. These specific environmental conditions were applied during the electrical conductivity measurements on the peridotites: p~ = 132-196 g2m and P~82~ = 313-357 g2m. These results are discussed and correlated to those literature data which were taken from in situ electrical soundings.