Quaternized poly(propylene imine) dendrimers have been prepared and investigated for their ability to function as pH-responsive controlled-release systems. These functionalized dendrimers are able to solubilize pyrene due to charge transfer complexation between the probe and the tertiary amino groups of the dendrimeric branches. The introduction of the quaternary ammonium groups at the external surface of the dendrimers affects the protonation titration profile as compared to the parent compounds leading to the release of the entrapped pyrene within a narrow pH region and basically when the intermediate nitrogens are protonated. These properties render these materials promising candidates for pH-responsive controlled-release systems possibly including prospected drug delivery applications.