The response of human melanocytes and melanoma cells to hydrogen peroxide stress was measured. Cells were exposed to glucose/glucose oxidase or free H2O2 and reactive oxygen species measured by luminol-enhanced chemiluminescence. The response was distinctly different between the two types and the addition of superoxide dismutase to melanoma cells paradoxically enhanced the chemiluminescent signal. These findings coupled with other known differences between the way these two types of cells handle oxidative stress at a molecular level suggests that a therapeutic window may be available for exploitation.