The precipitation of Mg2Si on the surface of Al 6022 has been investigated in situ using a Confocal Scanning Laser Microscope and a gold image furnace during cooling and isothermal conditions. It was found that precipitates form during cooling at temperatures between 400 and 280degreesC. The numbers and size of precipitates, as well as the growth velocity have been obtained as function of temperature for different cooling rates. The growth of precipitates has been modeled by means of a normalized Gaussian function, which can be used to predict the precipitate evolution.