The invention relates to a device for injecting precursors as gases/vapours, used in a laser pyrolysis installation for obtaining nanoparticles/nanostructures. According to the invention, the device for injecting precursors provides the introduction of precursors in the synthesis area, upon the interaction with the laser radiation, according to the conditions required by the synthesis area, and it consists of a thermostatic system providing the precursor temperature control by means of a thermocouple (TCU), to prevent condensation process, of some disks: an end disk (DC) and some disks (D1, D2, D3, D4) which, are assembled to materialize the channels (a, b, c) for conveying the precursors and to provide tightness of the injection system, both among the precursor channels and inside or outside the reaction chamber, the injection device being provided with highly flexible systems for connecting it to the reaction chamber and systems for processing the precursors with ultrasounds and by barbotage, the components of the mentioned injector ensuring the processing of dangerous, toxic, pyrophoric materials, at temperatures specific to the synthesis process.