We present a species-specific Mg/Ca-calcification temperature calibration for Globorotalia inflata from a suite of 38 core top samples from the South Atlantic (from 8S to 49S). G. inflata is a deep-dwelling planktonic foraminifer commonly occurring in subtropical to subpolar conditions, which qualifies it for reconstructions of the permanent thermocline. Apparent calcification depths and calcification temperatures were determined by comparing measured δ¹⁸O with equilibrium δ¹⁸O of calcite based on water column properties. Based on our core top samples, G. inflata apparent calcification depth is constant throughout the South Atlantic midlatitudes with a depth of 350-400 m within the permanent thermocline. The resulting Mg/Ca-calcification temperature calibration is Mg/Ca = 0.72 0.045/0.042 exp (0.076 0.006 calcification temperature) (r² = 0.81) and covers the temperature range 3.1°C-16.5°C. We applied our Mg/Ca calibration to gravity core PS2495-3 from the Mid-Atlantic Ridge at ∼41S to test its validity by reconstructing a low-resolution record covering the last two glacial-interglacial cycles. Our paleotemperature record reveals large changes in temperature for Terminations I and II, when permanent thermocline temperature increased by as much as 8°C. The G. inflata paleotemperature record suggests that oceanic fronts repeatedly migrated over the location of core PS2495-3 during the last 160 kyr. This study shows the potential of G. inflata Mg/Ca to reconstruct paleotemperatures in the permanent thermocline. Copyright 2011 by the American Geophysical Union.