As biodiesel production increases worldwide, so does the generation of its glycerol waste byproduct. Purifying the waste glycerol is difficult and energy intensive; it would be preferable to find a productive use for waste glycerol requiring little to no refining. Herein, we examine the use of waste glycerol from biodiesel production as a component in deep eutectic solvents (DESs). Specifically, we examine mixtures of waste glycerol and choline chloride (ChCl) as prototype simple and inexpensive DESs. The densities and viscosities of the waste glycerol derived DESs are consistent with those measured in DESs prepared with clean glycerol. DESs from waste glycerol are competent solvents for a classical Fisher esterification reaction and show utility in extracting methanol from crude biodiesel mixtures. These DESs therefore show promise as solvent systems, leading to a decrease in waste from the ever-increasing production of biodiesel and also serving as a value-added product for biodiesel manufacturers. (C) 2015 Elsevier B.V. All rights reserved.