In recent years, there has been a growing interest in the singlet form of oxygen as a regulator of the physiological functions of cells. One of the ways to generate singlet oxygen is direct optical excitation of the triplet oxygen form. Since molecular oxygen weakly absorbs light, high power is required to obtain sufficient concentrations of singlet oxygen. However, the increase in the radiation power of laser can induce a local temperature increase around the laser spot. This may be critical considering the temperature governs every biological reaction within living cells, in particular. Here, the interaction of laser radiation of infrared wavelengths, generating singlet oxygen, with biological tissues and cell culture media was simulated. Using the COMSOL Multiphysics software, the thermal field distribution in the volume of skin, brain tissue and cell culture media was obtained depending on the wavelength, power and exposure time. The results demonstrate the importance of taking temperature into account when conducting experimental studies at the cellular and organismal levels.