We report on Surface Enhanced Raman Scattering (SERS) activity of silver colloids prepared by a radiolytic method followed by a chemical development by EthyleneDiAmineTetraAcetic (EDTA) acid. On these colloids, in presence of Rhodamine 6G and of EDTA, we have observed Single Molecule SERS spectra. We show that the spectra observed on single silver aggregates in presence of EDTA evidence a (photo)oxidative character of sites that exhibit a giant SERS enhancement. (C) 2004 Elsevier B.V. All rights reserved.