In the second webinar of our series, we will advance to unknown structure elucidation using computer assisted structure elucidation (CASE). CASE systems have significantly contributed to de novo structural elucidation of thousands of natural and synthesized compounds. Here, we will demonstrate how by using a molecular formula, CASE can find the chemical structure that best fits the spectral data. The steps taken during the process, including generation of a Molecular Connectivity Diagram (MCD), structure generation and ranking of results will be reviewed. Additionally, complicated cases such as structures with unexpected correlations, spectral ambiguity, hydrogen deficiency and symmetrical molecules will be discussed. Finally, we will demonstrate how a 3D configuration can be determined from a 2D structure.