Polyelectrolyte multilayer microcapsules are important for a variety of potential applications, and represent a convenient system for studying properties of multilayer films. Recent work explored a post-treatment of such capsules by organic solvents, by reporting a softening. Here we show, that an addition of a very small amount of solvent (THF) to the phosphorus [G(3)(NH+Et2Cl-)(48)] dendrimer adsorption solution results, in contrast, in a discernible stiffening of (PSS)/phosphorus dendrimer microcapsules, although it does not affect the multilayer thickness. Our results open new possibilities to tune mechanical properties of multilayer films. (C) 2010 Elsevier Ltd. All rights reserved.