Deep eutectic solvents (DESs) consist of a mixture of two or more compounds and have a melting point significantly lower than their components. Deep eutectic solvents (DES) can be tailored by adjusting the structure or ratio of their precursors, thus enabling a wide spectrum of potential applications, including extraction, separation, and electrochemical processes. Their desirable properties, such as low toxicity, biodegradability, low cost, and versatility, have made them an attractive alternative to traditional organic solvents. However, there have been concerns regarding their high viscosity and challenges in regeneration and separation from the reaction medium. Moreover, not all DESs are inherently non-toxic or biodegradable, which raises questions about their sustainability. This chapter addresses the current challenges in the applications of DES and aims to provide valuable insights into the integration of DESs in real industrial settings.