The evaluation of mercury concentrations in surface waters and sediments is the main objective of this study. Once in the environment, this toxic element can be transformed by bacteria from a less toxic compound, the inorganic mercury, to a more toxic organic form, with harmful effects, when present in fish and wildlife in general, where could bioaccumulate and biomagnify. People may be exposed to mercury in any of its forms under different circumstances, like consumption of fish. The evaluation of this metal, respond to MONITOX project objectives, being one of the toxicants to be studied in MONITOX Network. In 2019, during the national and joint trip, there were taken 36 surface water samples and 32 sediment samples. After microwave digestion, the samples were analyzed using the cold vapour flameless atomic absorbtion FIAS instrument,that assures full automation, high speed of analysis and minimum sample consumption. The concentrations were reported to Romanian legislation and it can be observed that the mercury concentrations from the surface waters are between 0.1 μg/L - 0.3 μg/L (values corresponding for very good ecological status and good ecological status) and for sediments are below the quality standard of 0.3 mg/kg. Comparing the results, it can be observed relatively low concentrations from Calarasi to Galati, followed by an increasing from Galati to the Black Sea. Also, it were computed the Pearson correlation coefficients, between the mercury concentrations determined in surface waters and sediments samples and it was observed good correlation, that indicates the increasing of mercury concentrations in surface waters determined the increasing of mercury concentrations in sediments. Acknowledgement: We acknowledge the funding from ENI project eMS code BSB27 MONITOX (2018-2021), Joint Operational Programme Black Sea Basin 2014 - 2020.