A theoretical study based on density functional theory (DFT) at the B3LYP/LANL2DZ level was carried out to investigate the ability of a colorimetric sensor array (CSA) to bind volatile organic compounds (VOCs). Copper porphyrin (CuP) is the common dye that is used to represent a CSA in this study. There are three possible spin states for CuP and CuP-VOCs, namely, singlet, triplet, and quintet. However, the ground state for CuP is the triplet state, except for CuP-O2. This theoretical study reflects that CuP is very sensitive to N2 necessitating a change of the carrier gas from N2 to another gas. The ability of CuP to bind VOCs can be classified into three levels on the basis of binding energy. The results of this study suggest that theoretical investigations will be useful for optimizing the CSA sensor for a specific analyte.