In my research work I focus on studying the process of photoinduced electron transfer in biomolecules using quantum chemical methods. The main part of my research concerns the correct description of these processes using different methods in systems that are fragments of nucleic acids. I study how stacking interactions between the nucleobases affect the stability of excited states of different characters and electronic couplings between these states. I also study the role of photoinduced electron transfer in astrochemical reactions.