Ultrafast dissociation of excitons in US quantum dots via electron transfer to adsorbed rhodamine B (RhB) molecules was demonstrated. The rate of electron transfer can be controlled by the number of adsorbates attached on the nanoparticle and transfer time as fast as 12 picoseconds was observed. The rapid and controllable charge separation in this model quantum dot-adsorbate complex provides a potential approach for separating multiple excitons before the exciton-exciton annihilation process.