The transformation products of benzylidene acetone formed during zinc electrodeposition in solutions containing a nonionic surfactant and/or carboxylic acid were determined by IR and H-1 NMR-spectra after extraction and chromatographic separation. 1-Phenylbutanone-3, 1-phenylbutanole-3 and 1-phenylbutans were cathodic reaction products. Benzaldehyde, acetone, benzyl alcohol and benzoic acid were chemical reaction products in the cathodic layer. The nonionic surfactant increased the solubility of benzylidene acetone and carboxylic acid. This effect is probably caused by hydrophobic interaction and formation of associates, The associates cover a larger area of the cathodic surface than unsaturated ketone and/or carboxylic acid alone. It is supposed that a synergistic effect of additive mixtures on zinc electrodeposition may be caused by the formation of associates.