The quantum chemical calculations using DFT were performed for 2-alkyl-4X and 2,6-dialkyl-4-X substituted phenols. Based on the optimal geometries the bond dissociation enthalpies (BDEs), proton enthalpies (PAs) and the lipophilicities were computed. Additionally, simple geometry parameter was found correlating well with experimental leukemia cell toxicity of substituted phenols. Next, we have found no linear dependence between PA or BDE values and log1/C values in gas phase or in water despite the radical toxicity mechanism proposed in the literature.