In the current study, carboxylic acid-based deep eutectic solvent including a hydrogen bond donor (acetic acid) and a hydrogen bond acceptor (menthol) has been synthesized and applied for the removal of diclofenac from its aqueous medium. Physical properties (acidity, density, viscosity, and refractive index) of the synthesized liquids were determined quantitatively. The designed deep eutectic solvent was also characterized by Fourier transform infrared spectroscopy method. The removal of diclofenac has been reached to approximate to 80% through the proposed solvent system of reactive liquid extraction. Initial DIC concentration (9.87, 20.29, 29.44, 38.83, and 48.28 mg L-1), deep eutectic solvent level (0, 20, 40, 60, and 80%) in diethyl succinate, and the temperature (293.15, 303.15, 313.15, and 323.15 K) have affected the extraction efficiency. Ionic concentration in extraction medium leads to drop the diclofenac removal. Effects of fluorine and chlorine on the removal of diclofenac have been also investigated. Thermodynamics of the diclofenac transfer from aqueous environment to organic phase containing deep eutectic solvent has been found to be a spontaneous and endothermic process, which is incentivized by entropy.