In this study a series of new benzimidazolium salts (2a-c) were synthesized from the reaction of 5,6-dimethyl-1-(alkylbenzyl)-1H-benzo[d] imidazole with various alkyl halides. These salts were used to synthesize cupper N-heterocyclic carbene (Cu-NHC) complexes 3-4. The obtained (NHC) Copper (I) complexes 3-4 were characterized by FT-IR, NMR (H-1 and C-13) spectroscopic methods, mass spectrometry (EI-MS and HRMS) and elemental analysis. These novel cupper complexes 3-4 were used as a catalyst for alkyne - azide cycloaddition (CuAAC) reaction. Several triazoles 7 have been synthesized. This catalytic system fulfils the requirements of "click chemistry" with its mild and convenient conditions, notably in water at room temperature with low catalyst loading and simple isolation with no purification step. (C) 2017 Elsevier B.V. All rights reserved.