The cytotoxic effect of catechol was examined in two human cancer cell lines, Epidermoid larynx carcinoma (Hep- 2), Cerebral glioblastoma multiforme (AMGM-5) and Murine mammary adenocarcinomacell (AMN3) treated with half concentrations of catechol (1000, 500, 250, 125, 62.5 and 32.25 μM) for 72 hr. The get hold of results showed catechol have a toxic effect of the cell viability of three types of cell lines after 72h of exposure, the toxicity was dependent on catechol concentrations and/or autoxidation for quinines formation, there were a marked decreased of cell viability in a dose dependent manner in all cell line types. Inhibition concentration of catechol for 50% of cell viability (IC50) were calculated, they were at 581.5 μM, 478 μM and 833 μM of HEP-2, AMGM-5 and AMN3 cells, respectively. In addition the combination affects of three cell lines treated with catechol (previously treated at three concentrations close to IC50 were125, 250 and 500 μM for cell lines were incubated for 24 hr.) were assay with 100ul superoxide Dismutase (SOD) , 500 ul peroxidase (POD) and theirs combination (100ul SOD and 500 ul POD) and 125 or 250 μg/mL of catechin against the toxicity of catechol in cell lines to estimated the reduction in quinine formation in these combinations, most inhibition rate of quinine formation display at 100ul SOD alone and combination with 500 ul POD in three cell lines in comparison to other treatments dependant to quinione formation in cells treated with catechol only. Higher percentage in inhibition rate of quinine formation were record in combination treatment of SOD & POD with three concentrations of catechol in AMGM5 cells (54.2%, 59.2% and 65%), followed Hep-2 (44.2%, 42.6% and 52.7%) and AMN3 in 38.7%, 46.6% and 50.7%, respectively, furthermore the less efficient protect obtained in treatment all cell lines with two concentrations of catechins.