The present study reports the effect new DFT methods introduced in Gaussian 16 viz B2PLYP, B2PLYPD, DSDPBEP86 and MPW2LPLYP on spectroscopic characterization and nonlinear optical properties (NLO) of 2-Bromo-5-nitrothiozole and Nitrosodimethylamine. The obtained results have compared with the old DFT as well as MP2 and HF. The spectroscopic characterization viz. geometrical parameters, vibrational, electronic absorption spectra and HOMO to LUMO gap with their molecular orbitals have been reported. The geometrical parameters such as optimized energy, dipole moment, bond length and angles have reported for both molecules at all methods using higher basis set (6-311++G**). The first and second order hyperpolarizabilities have also been reported for both 2-Bromo-5-nitrothiozole (C3HBrN2O2S) & Nitrosodimethylamine (C2H6N2O) molecules at all methods. This study shows that these two molecules are responsive to nonlinear optical (NLO), which reflect its enhanced applicability in development of photonic devices. The finite field approach has been applied for calculating first and second hyperpolarizabilities β and ϒ respectively. The HOMO to LUMO energy gap of Nitrosodimethylamine is found to be greater than that of 2-Bromo-5-nitrothiozole. All these calculations have performed using Gaussian 16 program package.