Abstract: Provided is method for synthesising core-shell nanoparticles by laser pyrolysis. The method may include a) conveying together a gaseous mixture including a silicon precursor and a germanium precursor in a reaction zone of a first chamber of a reactor, and b) emitting a first laser beam at the level of the reaction zone for carrying out a laser pyrolysis of the mixture, the steps making it possible to obtain nanoparticles having a core made of a silicon- and germanium-based alloy and a silicon shell.