Well crystalline gadolinium oxide(Gd2O3) nanostructures were grown by annealing the hydrothermally as-prepared nanostructures without using any template. Microscopic studies of Gd2O3 nanostructures were recorded along the [111] direction due to the clearly resolved interplanar distance d(222)~0.31 nm of the cubic crystal structure Gd2O3. Sensing mechanism of Gd2O3 as efficient electron mediator for the detection of ethanol was explored. As-fabricated sensor demonstrated the high-sensitivity of ~0.266 μAm/M/cm2 with low detection limit(~52.2 μmol/L) and correlation coefficient(r2, 0.618). To the best of our knowledge, this was the first report for the detection of ethanol using as-grown(at 1000 oC) Gd2O3 nanostructures by simple and reliable I-V technique and rapid assessment of the reaction kinetics(in the order of seconds). The low cost of the starting reagents and the simplicity of the synthetic route made it a promising chemical sensor for the detection of various toxic analytes, which are not environmentally safe. Microscopic studies of Gd2O3 nanostructures were recorded along the [111] direction due to the clearly resolved interplanar distance d (222) ~ 0.31 nm Sensing mechanism of Gd2O3 as an efficient electron mediator for the detection of ethanol was explored. As-fabricated sensor rendered the high-sensitivity of ~ 0.266 μAm / M / cm2 with low detection limit (~ 52.2 μmol / L To the best of our knowledge, this was the first report for the detection of ethanol using as-grown (at 1000 oC) Gd2O3 nanostructures by simple and reliable IV technique and rapid assessment of the reaction kinetics (in the order of seconds). The low cost of the starting reagents and the simplicity of the synthetic route made it a promising chemical sensor for the detection of various toxic analytes, which are not environmentally safe.