Gold and silver nanoparticles (AuNPs, AgNPs) exhibit outstanding optical properties due to their plasmonic behavior. One common route of producing such nanoparticles is to transform the precursor salts (HAuCl4, AgNO3) in presence of the surfactant CTAB.[1] Our recent small angle X-ray and neutron scattering (SAS) experiments support the existence of CTA-Br-Au complexes as catalytically relevant components for AuNP formation. Upon the addition of the precursors and the ligands ascorbic acid and thiourea, we found drastic differences in the diffuse SAS signal with respect to the aqueous CTAB solution indicating significant structural differences in the formed gold complex-modified micelles. This effect is even more pronounced if AgNO3 is used instead of HAuCl4 as precursor. The proposed SANS experiments will allow us to compare our results of HAuCl4 containing CTAB solutions to that with AgNO3 as precursors for nanoparticles. It will be possible to locate the single components of the micelles via contrast variation by using different D2O/H2O mixtures. This work will help to understand the noble metal nanoparticle formation in general. [1]T.K.Sau et al.,Adv.Mater.2010,22,1781-1804.