The Baksa Gneiss Complex is a polymetamorphic basement complex located in the southwestern part of the Pannonian Basin. It is mostly built by metapelites, amphibolites and marbles, penetrated by aplite dikes. Post metamorphic fractures are filled in with an epi+di+ab+kfp+chl+pyr+qtz+cc mineral paragenesis. Two dominant paleofluid types can be distinguished in the epidote, diopside and calcite crystals based on their fluid inclusions. The earlier one is characterized by low salinity (0.2-6.5 w% NaCl eqv.) and high temperature (Th: 127-362 °C) and relates to hydrothermal propilitc alteration. Primary and pseudosecondary incusions of the high salinity (18.2-26.5 w% NaCl eqv.) and low temperature (Th: 70-132 °C) late fluid indicate mixing of hydrothermal fluid with highly saline basinal brines.