All molecules were standardized and cleaned using built-in OCHEM workflow. Molecules were stripped from salts (only the largest component was kept for analysis), neutralized then returned as canonical SMILES for processing by various descriptor packages and machine learning methods. OCHEM stores molecules in Kekule representation. A conversion from aromatic to Kekule representation could sometimes result in error. We did not observe any errors with molecules downloaded from the challenge website. An analysis of the InChi detected one duplicated molecule (EOS17062/EOS102135) which was present in both training and test sets.