Abstract: Schiff base, 1-[2,4–dihydroxy phenyl] ethanone [RPT] Ligand is a new chromogenic reagent have not been used so far for the determination of copper and cadmium in trace quantities. Effect of pH on wave height for Cu-[RPT] and Cd-[RPT] systems have been studied at pH 6.5-11.0 in 0.1 M NaNO3, and 0.002 % Triton -X-100 which increases the stability of the complex. Effects of Ligand concentrations, height of mercury column, metal ion concentrations on Copper and Cadmium on wave height at pH 10.0 have been studied. The author also investigates metal-ligand ratio and stability constants of cadmium-RPT by reversible system.