This study provides for the first time the 96-h toxicity of 16 nitro- and methyl-substituted phenols to Chlorella vulgaris. Enabling the circulation of new ecotoxicity data has expanded the previously reported toxicity data set of 30 phenols to C. vulgaris by our laboratory. In this respect, high quality, single source algal toxicity data, generated in the same laboratory according to a REACH (Registration, Evaluation, Authorization and Restriction of CHemicals) compatible endpoint, provided a sound basis to explore quantitative structure-toxicity relationship (QSTR), which can be used for regulatory purposes. Of the developed linear models on a new data set, the selected one was applied to a data set lack of toxicity values, and prediction ability of the model was discussed. Interspecies relations were sought related to Pseudokirchneriella subcapitata and Tetrahymena pyriformis. The developed models displayed decent predictivity, which can be used to predict the toxicity of untested phenols on C vulgaris. (C) 2017 Elsevier B.V. All rights reserved.