A comparative study of structure, energies and spectral analysis of Succinimide, N-hydroxy-succinimide (NHS) and N-methyl-succinimide (NMS) has been carried out using density functional method (DFT/B3LYP) with 6- 311++G(d,p) as basis set. To determine lowest-energy molecular conformation of NHS and NMS molecule, the selected torsion angle is varied and molecular energy profile is calculated. The molecular electrostatic potential surface, electric dipole moment, polarizability and the first hyperpolarizability values of Succinimide, NHS and NMS have been calculated at the same level of theory and basis set. The thermodynamic properties of the studied compounds at different temperatures were also calculated.