Аннотация:In this work, laser spectroscopy was used to study reverse microemulsions, in which the reactionof ZnS nanoparticle synthesis was carried out. The sizes of the synthesized nanoparticles do not exceed 5 nm.As a result of studying the processes in the reaction medium, it was found that the band of stretching vibrations of HS– ions in the region of 2568 cm–1 is an identification sign of the synthesis of nanoparticles: by itsintensity it is possible to determine the stage and completion of the ZnS synthesis.