Abstract: A portable hydrogenator designed for neutron scattering measurements is developed. The factors of performance, operation, maintenance and safety etc. have been taken into account in the design. The hydrogenator can be used not only in the conventional p-c-T isotherm measurements, but also in the in-situ neutron diffraction measurements for hydrides (deuterides) during hydrogenation. In order to insure high quality of the data from in-situ measurements, the null-matrix Ti-Zr alloy and the austenitic steel with high Mn content have been used in the sample cells, and the cells have designed to be disconnectable from the hydrogenator under pressure seal. Computer control has been realized in monitoring the temperature and pressure changes during experiments, and a relevant computer program has been developed to correct the temperature and pressure effects, and reduce the bias errors of the system. The hydrogenator has been successfully used in the in-situ diffraction experiments on several deuterides.