The effects of some new organic additives, such as horse-chestnut extract (HCE) and a mixture of ethoxyacetic alcohol and triethyl-benzyl-ammonium chloride (IT-85) upon the morphology and structure of copper deposits, as well as upon the cathodic polarization, are investigated and compared to those exerted by thiourea and animal glue, in the case of pure, synthetic sulphate solutions. The additive IT-85 was found to be an efficient inhibitor of the copper electro-crystallization process, leading to levelled, fine grained cathodic deposits with a strong [110] texture. The effects of HCE were similar to those exerted by animal glue, leading to deposits consisting of rounded nodules, without a clear texture, reflecting a smaller levelling effect.