The thermal scattering data for H in H2O are adjusted to better fit a series of criticality safety benchmarks using the Petten adjustment method for optimizing nuclear data. This method is based on the “Total Monte Carlo” approach developed for nuclear data uncertainty propagation to a large-scale system, together with a selection based on a global distance to specific criticality benchmarks. This paper demonstrates the possibility to improve the agreement with integral benchmarks by modifying the thermal scattering data. It is an additional step toward defining a globally adjusted nuclear data library with the Petten adjustment method, including thermal scattering data and nuclear data at higher energy.