AbstractA deep blue colored chelate compound resulting from the reaction between copper ion and glutamate was studied polarographically and spectrophotometrically.A single reversible wave corresponding to the reduction of the copper‐glutamate complex to the Cu(I) state was observed in thepH range 4.5 to 6.7.Only one kind of chelate compound, CuG2= was detected. The electrode reaction is formulated thus CuG2= + H++e=CuG−+ HG−The diffusion current constant is 3.13 for 0.2Mglutamic acid and 0.1Mpotassium chloride atpH 6.2.The copper‐glutamate complex (1:2) has an absorption maximum at 615 mμ. and its absorbance was constant at the widepH range 4.2 to 9.2. Its instability constant was calculated to be