In this work, the determination of pentahydroxyflavones on a glassy carbon electrode modified with chitosan and multi-walled carbon nanotubes (Ch-MWCNT) was studied. The presence of ionic liquids (Us) on the surface of the modified electrode (Ch-MWCNT-LI-GCE) increased the oxidation current by nearly 20%. The pH and electrochemical parameters (adsorptive potential and time accumulation) were optimized based on the oxidation of morin to obtain the following values: pH, 3.2; E-ads, -0.10 V; and t(ads), 70 s. The detection limit was 0.54 x 10(-7) mol L-1 and the RSD was 1.7%. The new method was used to quantify pentahydroxyflavones in plant tissue samples. (C) 2015 Elsevier B.V. All rights reserved.