The quantum chemical study of phenols cytotoxicity extended to their metabolites is presented. Based on O-H bond dissociation enthalpies (BDE) and octanol-water partition coefficients (Log P) calculated using density functional theory (M06-2X and B3LYP functionals) with 6-311++ G(d, p) basis set, their toxicity, in terms of Log (1/C), is described. The characterization of quinoid metabolites is also performed. Observed toxicity of phenols can be correlated with the properties of their ortho-quinone oxidation products/metabolites, i.e. Log P and partial atomic charges at C2 or O2 atoms, too. Found results indicate that ortho-quinones contribute to the overall experimentally determined toxicity of phenols.