The aim of the study is to investigate the effects of solvent polarity on the frontier molecular orbitals energy gap and global chemical reactivity of Tetrathiafulvalene in order to understand the stability and reactivity of Tetrathiafulvalene in a different solvent medium. Density functional theory with (B3LYP/6-311++G) basis set was used to perform a variety of calculations in both the gas and solvent phases. Besides dipole moment, Mulliken charge distribution, and thermodynamic properties were calculated in five solvent phases namely (water, acetone, Tetrahydrofuran (THF), Carbon tetrachloride (CCl4), and benzene). The calculations were carried out using the Gaussian 09 software, and the results showed that the solvents have an effect on the optimized parameters. Moreover, Mulliken population analysis, and local reactivity as Fukui Functions (FFs) from the natural bond orbitals (NBO) charges are computed to understand the electrophile, nucleophile region, and chemical activity of the title molecule. The dipole moment in gas phase and solvent medium is 0.00 Debye. Also, it was observed that the global chemical reactivity parameters change depending on the molecular structure and polarity of the solvents. Tetrathiafulvalene molecule was observed to have greater stability (low reactivity) in the water solvent with an EHOMO-ELUMO energy gap of 3.946 eV while it has higher reactivity (low stability) in the gas phase with EHOMO-ELUMO energy gap of 3.872eV. finally, this result indicates that Tetrathiafulvalene is an excellent candidate for future studies of semiconductor and optoelectronic materials.