Apatite fission track age data from the majority of the 14 samples studied indicate cooling below c. 110 degrees C beginning 60 to 90 Ma ago. Vitrinite reflectance modelling suggests temperatures prior to cooling reached > 160 degrees C in the north and 150 to 160 degrees C elsewhere. Temperatures from fluid inclusions in quartz cement from the Carboniferous Nordkapp Formation may have reached 139 to 151 degrees C. Zircon fission track data from the basement indicate that the maximum temperature during Hecla Hoek metamorphism was less than 290 degrees C. Circumstantial evidence suggests that temperatures prior to deposition of the Permian Miseryfjellet Formation were probably much lower than those during the Mesozoic. Maximum eroded overburden above the Miseryfjellet Formation can be estimated at 2900 to 4200 m using various different methods. The resulting geothermal gradients suggest palaeoheat flow conditions close to those of today.