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Unplanned abstraction of groundwater due to various land use land cover activities and variations in monsoonal rainfall have greatly affected the availability and quality of groundwater resources in semi-arid regions of India. In the present study, a study of the hydrogeochemical characteristics of groundwater was undertaken in the Sonipat district of Haryana in India together with the use of stable isotope (delta O-18 and delta D) measurements and GIS analysis. A total of 53 groundwater samples were collected from seven blocks of the district, and 14 water quality parameters and stable isotopes (delta O-18 and delta D) were analysed to infer hydrogeochemical processes taking place in the area. The integration of hydrochemistry with GIS is very helpful to understand the factors governing in the area. The majority of the samples showed Na-Cl type of hydrochemical facies. The trilinear plot for major cations and anions in groundwater indicates dominance of sodium, calcium, chloride and bicarbonate ions. Nitrate plumes in the groundwater appear to be migrating in groundwater from the central and south-western parts of the area towards the urbanized areas. A total of 64% of the samples exceed the maximum permissible limit of 1.5 mg/L given by WHO for fluoride. Besides natural sources such as silicate and carbonate weathering, ion exchange, and reverse ion exchange, the leaching of surficial salts and untreated industrial wastes along with unregulated abstraction are contributing to poor groundwater quality in the study area. An assessment of saturation indices has shown that groundwater in the area is unsaturated with respect to anhydrite, halite and gypsum suggesting significant contribution of Ca2+, Mg2+ and other ions in the groundwater. A scatter plot of delta O-18 versus Cl also suggests mixing of saline water with fresh groundwater.