Abstract: The present invention relates to copper complexes exhibiting superoxide dismutase-like activity in mammalian cells. The copper complexes, which act as superoxide radical (O.sub.2.sup.-) scavengers, are used in treating cancer by replacing the lost superoxide dismutase activity which characterizes tumor systems. The low molecular weight and lipid solubility of the copper complexes facilitate penetration of cell membranes. Depending upon the specific type of copper complex used, treatment may result in decreased tumor growth, increased survival of the host organism, decreased tumor metastasis or induced morphological differentiation of cancerous cells. The copper complexes used according to the invention include copper salicylate complexes, their solvates as well as mixtures thereof. A method for the treatment of cancer using these copper complexes is also disclosed.