A series of DSILs with varying molar fraction of dicamba anion was prepared by mixing the ethanolic solutions of single-ion ILs. First, 0.05 mol of each parent IL (weighed with the accuracy of ±0.0001 g) was dissolved in ethanol to obtain 50 cm 3 of solution, and then both solutions were combined in such volumes as to obtain DSILs with the following MCPAdicamba molar ratios: 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, and 1:9. To ensure full reproducibility of the results for all DSILs, the same single-anion ILs solutions of a well-defined concentration (1 ±10 -5 mol dm -3 ) were used to obtain the solutions, which were dispensed using the same precalibrated automatic pipette. The obtained mixtures were vigorously stirred for 5 min, and then the solvent was evaporated. The products were pre-dried under reduced pressure conditions (5 mbar, 75 °C) analogously as for single-anion ILs. For analytical purposes, a significant amount of water was removed from the obtained products by two-step azeotropic distillation. The obtained product was dissolved in 30 cm 3 of 2-propanol, after which the azeotrope and the remaining 2-propanol were evaporated under reduced pressure. The residue was dried using a Schlenk line (pressure: 2•10 -5 bar) while heating to 65 °C for at least 6 hours. Subsequently, the residual 2-propanol was removed by performing azeotropic distillation with methanol and drying the residue as in the previous step. The obtained DSILs were stored analogously as in the case of their parent ILs. After drying, using a dicamba-derived single-anion IL and a DSIL containing 0.9 molar fraction of dicamba anion, 2 additional DSILs with molar ratios of MCPA and dicamba anions of 5:95 and 1:99 were also obtained for additional spectral studies according to an analogous method.