A wide variety of nanomaterials and associated nanomaterial/polymer composites are being developed in an effort to produce higher efficiency organic solar cells. This development requires a fundamental understanding of the energy levels for the individual materials, and their composites, to enable device designs which posess appropriate energy level matching. Cyclic voltammetry (CV) allows for the determination of the band gaps (Eg) and energy levels of these various nanomaterials and composites by measuring their oxidation and reduction potentials. These potentials correspond to a given material's ionization potential (IP) and electron affinity (EA), respectively. The results for the EA, IP, and Eg have been determined by CV for derivatized fullerenes and CdSe quantum dots (QD), measured in isolation, and in conjugated polymer composites with MEH-PPV. In addition, CV measurements conducted under dark and illuminated conditions were used to investigate the relationship between energy levels within the composites.