The interaction of gelatin with Mn^2+,Co^2+,Ni^2+ and Hg^2+ ions were investiged at different temperatures by fluorescence quenching method. The quenching constants, chelate equilibrium constants, binding sites and the thermodynamic functions are calculated.The results of micro- IR and UV show that Co^2+,Mn^2+and Ni^2+ interact with the amido bond in gelatin molecule. The entropy change is a main factor in the flurescence queching process of gelatin by Co^2+, Mn^2+ and Ni^2+.

Key words: METAL ION, THERMODYNAMIC FUNCTION, CHELATES, GELATIN, INTERACTIONS, TRANSITION METAL COMPOUND