Carbon and oxygen stars evolution in post-AGB phase

Despite many studies, the post-AGB phase is still not well understood. To make progress in this field, we searched for information about proto-planetary nebulae and built a catalogue of post-AGB objects. Based on collected data we were able to trace the evolution of stars in their late stages making a distinction between carbon and oxygen-rich objects. We focused our attention on spectral features seen in ISO data and clues for AGB nucleosynthesis. Together with the newest HST images of post-AGB objects we can study correlations between morphological types and chemical and physical properties of stars to improve our understanding of stellar evolution.