AbstractThe polarography of Nickel (II) in the presence of DL‐tryptophan has been studied in KNO3supporting electrolyte. Nickel yields two irreversible steps which are due to the formation of two varieties of complex in sluggish equilibrium with each other. The reduction is an irreversible, kinetically controlled process as evidenced from cyclic voltammetry and i–t curves. Rate constants of the processes are evaluated. The effect of temperature is descri