Abstract: Considering the growing problems related to climate change and environmental pollution, in this research the impact of the addition of silica nanoparticles (SiO2) on the chemical, surface and morphological properties of mixtures with different proportions of biodegradable polymers were tested. Biodegradable polylactide (PLA) and polycaprolactone (PCL), which could find their purpose in the making of letterpress printing plates, were used. In the mixture, the PLA was a continuous phase, while the PCL was a dispersed phase. Previous research has shown that the addition of silicon dioxide nanoparticles can change the interfacial properties of two polymers, i.e. nanoparticles act as a compatibilizer and contribute to better miscibility of two, otherwise immiscible polymers and thus affect the functional properties of the mixture. The aim of this paper was to examine the influence of SiO2 nanoparticles on the chemical, surface and morphological properties of a PLA and PCL mixture. FTIR-ATR spectroscopy was performed in order to get insight whether the silica has had an effect on chemical changes within the mixture. Surface free energy was determined from contact angle measurements, and SEM microscopy was performed to provide insight into the morphology of the samples itself.