The neutron capture cross section of 237Np was measured from 0.01 eV to 200 keV. The capture cross section was normalized at 0.0253 eV to a value of 180 ± 6 b derived from previous total cross-section measurements in the resonance region of neutron energies and the shape of the present data from 0.0253 eV to the resonance region. Resonance parameters were derived for the neutron energy region from 0.01 to 100 eV. Agreement with ENDF/B-V is poor in the thermal region (6.4%), excellent in the resonance region (∼2%) except for the 0.491-eV resonance, and good (∼5%) in the keV neutron energy region. An uncertainty analysis including a correlation matrix for group-averaged cross sections is presented. These results are important both for thermal and fast reactor applications and the calculation of 238Pu production, an intense alpha emitter.