This course is dedicate to deal with Isotope geochemistry. It is fundamental for interpreting the origin and evolution of sedimentary basins. Stable isotopes of carbon and oxygen reveal paleoenvironmental conditions such as temperature, salinity, and diagenetic alteration. Sulfur and strontium isotopes trace fluid sources and redox conditions. Integrated with petrographic and geochemical data, isotopic studies offer a quantitative framework to reconstruct sedimentary basin history, including diagenesis, fluid flow, and hydrocarbon or mineralization processes.