The interaction between the anionic surfactant, sodium dodecyl sulfate, and the polyelectrolyte, poly(diallyldimethylammonium chloride), may lead to formation of nanoparticles dispersed in water. The morphology of the resulting nanoparticles and their ability to solubilize hydrophobic molecules were evaluated. As shown by SEM and AFM imaging, the particles are spherical, having a diameter of about 20 nm. The solubilization within the nanoparticles was tested with pyrene, a fluorescence probe, and Nile Red, a solvatochromic probe. It was found that for Nile Red the solubilization within the nanoparticles is at lower polarity than for SDS micelles, and from pyrene solubilization it appears that the hydrophobicity of the nanoparticles depends on the ratio between the SDS molecules and the charge unit of the polymer. (c) 2005 Elsevier Inc. All rights reserved.