The aim of this work was to study the inhibition and deactivation of commercial enzyme cocktail (Cellic (R) Htec2) in the presence of [bmim][Cl] ionic liquid employing model cellulosic substrate, carboxymethyl cellulose (CMC). It turned out from the experiments - relying on enzyme kinetics approach - that [bmim][Cl] could act as a competitive inhibitor. Furthermore, depending on the process conditions i.e. contact of enzyme solution with high concentration [bmim][Cl], severe biocatalyst inactivation should be also taken into account as a potential risk during the enzymatic cellulose hydrolysis even in as short process times as few minutes. (C) 2017 Elsevier Ltd. All rights reserved.