The thermophysical delineation of four diol (glycerol, 1,2 butanediol, 1,6 hexanediol, and ethanediol)-based deep eutectic solvents (DESs) were investigated in the temperature range of 273-323 K at atmospheric pressure. The homogenous mixture was prepared with quaternary ammonium salt and diols, respectively, at an identical molar ratio of 1:1 (HBA/HBD). Density and viscosity have a negative response with increasing temperature. Conductivity and excess molar volume ratio increase at elevated temperatures. The results obtained were correlated with linear model equations. The liquid liquid equilibrium of the ternary mixture formed with PEG (6000) + Na2CO3 + DES was measured and correlated with the Merchuk equation. It is inferred from the data that the molecular weight and complex molecular nature of the HBD have a positive influence on the physicochemical properties of DES and its biphasic separation.