The Density Functional Theory (DFT) method was employed to study the properties of the C[Formula: see text] complex with tetraphenylporphyrin (TPP). Calculations were performed in vacuum and in the presence of different solvents. Strong interaction between the C[Formula: see text] cluster and TPP molecule was observed. To understand the effect of C[Formula: see text] on electrochemical properties of TPP, electron transfers from and toward the porphyrin and C[Formula: see text]-TPP complex were studied. It was shown that the presence of C[Formula: see text] influences the electron transfer reaction toward the porphyrin molecule and causes transfer of one and two electrons to C[Formula: see text]-porphyrin, which is more favorable compared with porphyrin alone. However, C[Formula: see text] has slight effect on electron transfer from porphyrin and on positive ion formation. The effect of solvent type on electron transfer energy was studied for these reactions, and it was shown that solvents with higher permittivity have lower electron transfer reaction energy, which may be predicted from ionic character of the products.