Images of Neptune have been obtained in the thermal range, in filters between 8 and 19 μm, using the VISIR mid-infrared imaging spectrometer at the VLT-UT3 (Melipal). They allow, for the first time, mapping of atmospheric temperatures at different altitude levels, rang-ing from the tropopause to the stratosphere. It was found that the south pole of Neptune, at the level of the tropopause, appears to be warmer than the rest of the planet by 6 to 8 K. This south-ern polar warming can be explained by its constant solar illumination over the past 40 years, as the southern summer solstice occurred in July 2005. The other unexpected discovery is the evidence for a stratospheric hot spot located at 65-70°S which rotates with the planet at the atmospheric rotation rate of about 12 hours.