[en] Highlights: • La_2O_3 and La_2O_3:Eu"3"+ nanoparticles are synthesized by low temperature sol–gel method. • Gamma irradiated TL glow curve of La_2O_3:Eu"3"+ shows linear response with dose. • TL emission shows bright red emission at 619 nm. - Abstract: Undoped and Eu"3"+ doped La_2O_3 nanophosphor are synthesized by low temperature sol–gel technique. The synthesized samples are characterized by X-ray diffraction (XRD) and average crystallite size is found to be ∼18 nm and ∼23 nm for undoped and Eu"3"+ doped La_2O_3 respectively. Gamma ray irradiated undoped La_2O_3 shows high intense thermoluminescence (TL) glow peak at 640 K and weak TL glow peak at 443 K and the high intense peak intensity is sub linear increase with γ-dose. Whereas Eu"3"+ doped La_2O_3 nanophosphor show a prominent TL glow peak at 640 K and its TL intensity linearly increases up to 1 kGy. The kinetic parameters are estimated using glow curve deconvoluted (GCD) technique. TL emission of γ-ray irradiated Eu"3"+ doped La_2O_3 show peaks at 508, 586, 619 and 706 nm are attributed to Eu"3"+ transition peaks.