we are reporting two methods for detection of Cu ion and Hg ions using biosynthesized silver nanoparticles. The detection of Cu ion was base on changes in absorbance resulting from complex formation of the metal ion. Various concentrations of Cu ion were used to test the linearity and sensitivity of the method. A new peak at around 770 nm, in addition to the peak of the AgNP at 406 nm, was observed in each case (above 20 L).