A portable hydrogenator designed for neutron scattering measurements was developed. The factors of performance, operation, maintenance and safety etc. were taken into account in the design. The hydrogenator can he used not only in the conventional p-c-T isotherm measurements, hut 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 were used in the sample cells, and the cells were designed to he disconnectahle from the hydrogenator under pressure seal. Computer control was realized in monitoring the temperature and pressure changes during experiments, and a rele- vant computer program was developed to correct the temperature and pressure effects, and reduce the bias errors of the system. The hydrogenator was successfully used in the in-situ diffraction experiments on several deuterides.