Through substrate vias (TSVs) are a seminal component of three-dimensional (3-D) integrated circuits (ICs). Each TSV typically carries a single signal between two adjacent layers of a 3-D structure. A multi-bit carbon nanotube TSV is proposed in this paper to increase the number of I/Os among layers within 3-D ICs. The proposed multi-bit TSV can propagate multiple independent signals due to the high anisotropy of the carbon nanotubes. The electrical properties of each bit within a two-bit TSV and the electrical interactions between the bits are compared to a theory-based electrical model, exhibiting high accuracy. The passive elements deviate by up to 4%, and the S-parameters of the system deviate by up to 1.5% from numerical analysis. Capacitive coupling and leakage current between the bits of the two-bit TSV model have also been evaluated. The structure exhibits negligible noise coupling (less than 1%) and a peak leakage current of 631.7 μA.