The present work shows the influence of a low copper addition and that of an excess of silicon on the precipitation kinetics and on the precipitation sequence of pseudo-binary Al-Mg2Si alloys in the temperature domain where the beta' phase forms. To study this influence, three different alloys were studied. The precipitation kinetics were followed by thermoelectric power (TEP) measurements, while the structure and the chemical composition of the precipitates formed were determined respectively by High Resolution Transmission Electron Microscopy and by Energy Dispersive X-ray Spectroscopy nanoanalyses. It was shown that the presence of copper and of an excess of silicon affects the precipitation from a kinetic and structural point of view. Furthermore, a correlation between the TEP kinetics and the microstructural.