Recently, photodynamic therapy has been considered as one of the promising alternatives to classical antimicrobial therapy based on antibiotics, which has become less effective due to bacterial resistance. Flavin mononucleotide  (FMN), a vitamin B2 derivative, is a biocompatible, affordable drug with attractive photodynamic properties, including the generation of reactive oxygen species (ROS) that can target and disrupt bacteria. The integration of silver  nanoparticles, known for their antibacterial properties, could affect photochemical processes and potentially enhance the antimicrobial effectiveness of FMN. This study shows the results of an investigation into the conditions for the  formation of a complex between silver nanoparticles and FMN, as well as the influence of nano-sized silver on the photodegradation of FMN under light irradiation. This work presents the development of a method aimed at preparation of FMN-silver nanoparticles complex. The influence of silver nanoparticles on the fluorescent properties of FMN and the dynamics of its photodegradation was evaluated.