OASIS (Optical Absorption Setup for Ice Spectroscopy) is one of the few setups to study chemical processes in interstellar ice analogues using optical spectroscopy. The light of a broadband lamp is guided through an ice substrate onto a spectrometer where the light is dispersed. The technique allows to record electronic spectra and to monitor chemical reactions, in situ and essentially in real time. The method is not affected by water absorptions in the ice and as transition strengths are higher, OASIS allows to study low density ices. In the last years the focus has been on PAH containing water ice, as PAH are thought to be omnipresent in space. More recently, amino acids are studied as part of the PEPSci network, to investigate whether such important molecules would survive conditions as encoutered when transfering complex molecules to (exo)planets.