The goal of this work was to explore the applicability of deep eutectic solvents in biodiesel production process. Bi-odiesel was produced from waste cooking oil via base-catalysed transesterification. The efficacy of two base cata-lysts KOH and NaOH on the conversion of triglycerides into biodiesel was tested. Eutectic mixtures DES 1 (K2CO3 : C2H6O2 = 1 : 10) and DES 2 (C5H14ClNO : C2H6O2 = 1 : 2) were prepared. DES 1 was used for feedstock deacidification and DES 2 for biodiesel purification via extraction. Effects of DES 2 to biodiesel ratio and the extraction duration on free glycerol removal were tested. Samples were analysed using FTIR and 1H NMR spectroscopy. Synthesis of biodiesel was carried out for 3 h at 60 ° C with mass ratio KOH : methanol : oil = 1 : 40 : 100. DES 2 was effective for purification of biodiesel. Mass ratios 0.5:1 and 1:1 proved best and 45 minutes of extraction was enough to reduce free glycerol and increase the content of fatty acid methyl esters