Fluid inclusions archive the drip water from which the speleothem formed and can, therefore, give valuable insights into paleo-hydrological conditions. In the framework of a PhD project, an extraction and processing system for fluid inclusion analysis with laser spectroscopy was developed and characterized. Technical advances now allow determining δ¹8O and δ²H of microliter water amounts with high precision and accuracy. The analysis of stable water isotopes enables the determination of paleotemperatures using the classic carbonate thermometer as well as the application of the δ²H /T – relationship. Beyond direct temperature determination, the analysis of fluid inclusions provides information about karst water availability during stalagmite formation.