Polydimethylsiloxane belongs among polymeric organosilicon compounds which find utilization in many industries. Within telecommunication technologies, the primary use is in the field of encapsulation of electronic units, circuit boards, optical splice or optical cables. This article focuses on the use of polydimethylsiloxane (below PDMS) for its optical properties. We created test samples with a defined ratio of PDMS polymer and luminophore which can to radiate part of the absorbed energy in the form of light. LED (Light-Emitting Diode) with the wavelength range of 440 nm to 470 nm, which corresponds to a blue color in the visible spectrum, was used as the source of excitation energy. Used luminophore is Yttrium Aluminium Oxide: Cerium (Y3Al5O12:Ce). The output of the selected combination generates white light. The value of the chromaticity temperature determines the color of light. The output of article is a definition of the suitable ratio of PDMS and luminophore whose the emitted light has the range of chromaticity temperatures matching white light, for example, for lighting. A USB-650 Red Tide spectrometer and SpectraSuite software, which has chromaticity temperature and spectral characteristic as output, were used to finding the chromaticity temperature.