The partial hydrophobization of hydroxyl ethyl cellulose (HEC), by incorporating benzyl entities, was successfully performed. So, cavities with binding sites enable to encapsulate the copper ion (Cu(II)) by coordination interaction result from. The resulting product (BEC, DS ae 1) thus contained two types of chelating sites: 2,2'-oxydiethanol and 2,2'-(ethane-1,2-diylbis (oxy))diethanol. The complex formed upon reaction with Cu(II) (labeled CuBEC) was studied using UV-Vis spectroscopy, and the results indicate strong ligand-metal charge transfer transitions of O -> Cu. The chemical structures of HEC, BEC and CuBEC were characterized by FTIR and NMR (H-1, H-1 DOSY, C-13 DEPT-135 and C-13) and UV-Vis spectroscopy was investigated. Furthermore, the crystalline order and the thermal stability were studied based on XRD patterns and thermogravimetric analysis, respectively. The structural results indicated that the copper ion has been encapsulated in square planar geometry formed by the two oxygen atoms of free hydroxyethyl (unbenzylated), the oxygen of the osidic bond and that of the hydroxyl of C-3 of adjacent anhydroglucose unit. A theoretical study was conducted using Hartree-Fock and density functional theory computations; the experimental results were in good agreement with the Theoretical ones. [GRAPHICS]