This study presents a new approach to geobarometry by combining fluid inclusionand clumped isotope thermometry on carbonate minerals. The offset betweenhomogenisation temperatures of primary fluid inclusions with known compositionand temperatures of the host mineral allows a direct estimation of the fluidpressure at the time of carbonate crystallisation. This new approach is illustrated viahydrothermal dolomite samples from the Variscan foreland fold-and-thrust belt innorthern Spain. Clumped isotope analyses yield crystallisation temperatures (107–168°C) which are higher than homogenisation temperatures in corresponding sam-ples (95–145°C). The calculated pressure values suggest that dolomitizing fluidswere overpressured during formation of zebra dolomite textures, whereas lowerpressures are obtained for dolomite cement from breccia textures. This newapproach to geobarometry opens up the possibility of estimating the pressure ofcarbonate crystallisation and has potential applications in diagenesis, basin analysis,ore geology and tectonics.