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Gaussian-based HF/MP2 and DFT/B3LYP methods have been explored to study the microsolvation of glycine anion with water, [Gly]-[(W).sub.n], and 1-ethyl-3-methylimidazolium glycine ionic liquid (IL) with water, [EMIM][Gly][(W).sub.n], n = 1-6 and 12. The water molecules are either isolated or aggregated around [Gly]-and [EMIM][Gly]. Their electronic structures have been calculated clearly to verify the molecular state of [H.sub.2]O and the results were used to compare with experiments. The water effect on the interaction energies and local packing of [EMIM][Gly] is considered. We identified an important factor: the variation of [EMIM][Gly][(W).sub.n] polarity with the different numbers of [H.sub.2]O. As the amount of [H.sub.2]O increases, the polar network is continuously broken up. The dipole moments are changed to be lowest when the H-bonding ability of [Gly]- is almost saturated. Meanwhile, the nonpolar groups of the cation form an enhanced aggregation. Such observation can provide initial insights for the experimental nanostructural evolution in the IL-water mixtures. Key words: [EMIM][Gly]-[H.sub.2]O, H-bond interaction, vibrational mode, dipole moment. On a explore les possibilites d'utiliser les methodes a bases gaussiennes HF/MP2 ou de la theorie de la fonctionnelle de la densite (TFD), B3LYP, pour etudier la microsolvatation de l'anion glycine par l'eau, [Gly]-(eau)n et du 1-ethyl-3methylimidazolium-glycine ionique liquide, dans l'eau [EMIM][Gly](eau)n, n = 1-6 et 12. Les molecules d'eau peuvent etre isolees ou agregees autour des entites [Gly]-et [EMIM][Gly]. On a clairement calcule les structures electroniques pour verifier l'etat moleculaire du [H.sub.2]O et on a utilise les resultats pour fins de comparaison avec les donnees experimentales. On a considere l'effet de l'eau sur les energies d'interaction et l'empilement local du [EMIM][Gly]. On a identifie un facteur important: la variation de la polarite du [EMIM][Gly](eau)n avec le nombre de molecules d'eau. Lorsque la quantite d'eau augmente, le reseau polaire se brise continuellement. Le moment dipolaire varie d'une valeur minimale quand la capacite de formation de liaison hydrogene de l'entite [Gly]est pratiquement saturee. Par ailleurs, les groupes non polaires du cation forment une agregation mieux organisee. Une telle observation peut nous aidier a mieux planifier revolution nanostructurale experimentale des melanges de liquide ioniques-eau (LI-eau). [Traduit par la Redaction] Mots-cles: [EMIM][Gly](eau), interaction avec liaison hydrogene, mode vibrationnel, moment dipolaire., Introduction The research for alternatives to conventional solvents is partly driven by the need for 'green' chemistry and sustainable technology. Moreover, because of the potential for novel synthetic routes and [...]