This work aims to study the geochemical composition of the suspension and riverbed sediments, produced by hydrological erosion of soils and rocks. Eleven riverbed sediment samples were gathered along the four main rivers of São Miguel island, Azores. River waters were also sampled for study of the suspension sediments. From this data it was possible to ascertain a geochemical signature for the sediments showing appreciable variation in major elements concentration in regard to the watershed, alongside a stability of concentrations for minor and trace elements between different stations of the same river. The identification of the sediments, following the granulometric treatment, showed consistency regarding geochemical analysis. The identified mineral phases and lithic assemblages are compatible with both the geochemical data and the lithology variation along the river. The geochemical study of the suspension sediments revealed, from the four gathered samples, a strong similarity, closer between themselves than to the corresponding riverbed sediments. These various studies allowed an initial geochemical characterization and showed consistency with the existing geologic knowledge for the studied areas.