[en] Uranium is an important nuclear fuel for reactors. The more abundant ²³⁸U, which is fertile, is capable of serving as a source material for the production of fissile ²³⁹Pu in nuclear reactors by neutron capture followed by two beta decays. Neutron capture cross-section of the ²³⁸U is an important parameter for the design of any nuclear system based on ²³⁸U-²³⁹Pu fuel cycle. Therefore, it is necessary to have accurate knowledge of nuclear data of actinides such as yields fission products, neutron capture cross-sections and decay data including half-lives, decay energies, branching ratios etc. for the design of innovative reactor systems including fast breeder reactors and ADSs. In view of this, ²³⁸U (n, 2n)²³⁷U reaction cross-section has been determined using an activation and off-line γ-ray spectrometric technique at an average neutron energies of 8.04±0.30 and 11.90±0.35 MeV. The experiment was carried out using 14 UD BARC-TIFR Pelletron facility at Mumbai, India where in ⁷Li(p,n) reaction was used to generate neutron beam. The experimentally determined cross-section was compared with the latest available evaluated nuclear data libraries of ENDF/B-VII.0, JENDL 4.0, JEFF 3.1/A and CENDL-3.1 and found to be in good agreement. The ²³⁸U(n,2n)²³⁷U reaction cross section was also calculated theoretically using nuclear model based computer code TALYS 1.2 and compared with the experimental data. (author)