In a real-time scale, it has been investigated the polymerization process in photosensitive compositions based on oligourethanacrylates with various concentrations of photoinitiators by using the method of surface plasmon resonance. Experimentally determined were the speed of polymerization and induction period for the studied samples of photopolymerization compositions as well as their optimum ratio of components for the chosen illumination wavelength 407 nm. It has been ascertained that with increasing the concentration of photoinitiators Irgacure 651 and Irgacure 819 from 1 up to 2% the speed of polymerization is increased by 3 and 7 times, respectively, while the induction period is decreased by almost 2 and 10 times, respectively. The presence of Irgacure 819 in these compositions provides the highest polymerization speed and the lowest induction period, which is related with the optimal choice of the illumination source wavelength inside the absorption spectrum of initiator, and the competitive absorption in other components of the photopolymer composition is minimal. These investigations are useful for developing optimal compositions of the studied materials for using them in various branches of industry.