Environmental risk assessment procedures require acute and chronic toxicity values of hazardous chemicals. In this respect, the 96-h toxicity bioassays of nitro-, methyl-, methoxy-, chloro-, and nitrile-substituted phenols and anilines to Chlorella vulgaris were performed. Median inhibitory and low-toxic effect concentrations were reported. Significant correlations between acute and chronic toxicities were found for the chemicals in the data set regardless of mode of action. Consequently, linear models employing theoretical and empirical descriptors were developed for the prediction of NOEC and IC20. The outcome of the study will be beneficial in the risk assessments of organic chemicals and setting water quality standards by the regulators. (C) 2017 Elsevier B.V. All rights reserved.