One important aspect of aquatic chemistry is salinity, which has significant effects on the solubility of heavy metals and other physicochemical factors, such as pH, TDS, and EC. Salinity also has a significant effect on uranium (U) solubility, according to numerous studies. This chapter explores the relationship between salinity and uranium speciation and how it affects uranium solubility. While several oxidation states of uranium exist in nature, U(IV) and U(VI), which exhibit notably distinct behaviors in aqueous environments, are the most common oxidation states. The uranyl ion (UO22+) is the main form of U(VI), and it is more soluble and may form a variety of complexes than U(IV), which is usually insoluble and precipitates in reducing circumstances. Salinity increases influence the ionic strength, complexation dynamics, and anion competitiveness, all of which affect uranium solubility. This chapter focuses on evaluating the mobility and solubility of uranium in saline environments.