2-[2-(Ethylamino-4-chlorophenylaminothiazol)-5-oyl] benzothiazole is found to have antifungal and antibacterial activities promoting effect. The, 2-[2-(ethylamino-4-chlorophenylaminothiazol)-5-oyl] benzothiazole derivatives are the subject of considerable pharmaceutical and chemical interest. Theoretical information on the optimized geometry, and IR intensities were obtained by means of Density Functional Theory (DFT) using standard B3LYP/6-31G basis sets with Gaussian, 09 software package. The calculated geometries such as bond lengths, bond angle, dihedral angle atomic charges and intensities of Vibrational bonds of the titled compound were investigated. The IR spectra are obtained and assigned by vibrational analysis and found to be reliable compared with the experimental results. HOMO-LUMO energy gap shows the chemical stability of the molecule.