The scientific activity has been developed in the use of environmental isotopes in hydrogeology research studies, palaeohydrology and climate investigations, emphasis on the use of the ratios 2H/1H, 13C/12C, 15N/14N, 18O/16O and variation of groundwater 3H and 14C content. The work is being focused on the study of the quality of groundwater for Human supply and groundwater resources protection and management, through the identification and quantification of pollution sources traced by environmental isotopes and definition of the recharge areas. Through the isotope hydrology research area contributions to a better understanding of the dynamic evolution response in time of aquifer systems have been carried out. The several projects carried out since 1988, give answers to relevant scientific issues, such as the identification of the salts contamination in groundwater as sources of the groundwater degradation (natural or induced by man), in the reconstruction of the palaeoclimatic environments, in order to investigate the extent to which groundwater retains the signature of past recharge events and Human influence. Besides the isotope data obtained in the framework of the national network for isotopes in precipitation provides important information for hydrological investigations relevant for water resources inventory, planning and development.