A successful electrolytic synthesis of compositionally modulated multilayers with small sublayer thicknesses requires a planar growth mode. In that respect it was experienced that for the synthesis of NiP/Sn multilayers organic additives have to be added to the tin electrolyte. However not all organic additives seem to be active on the P-enriched NiP sublayers, resulting in a tin island formation instead of the 2D growth required. In this paper several commercially available organic additives are evaluated as well as "self-composed" ones. Potentiodynamic polarisation and potential-time measurements during pulse current deposition coupled with a morphological investigation by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) are discussed.