This paper summarizes the characterizations of neutron reference fields using radionuclide sources at the Institute for Nuclear Science and Technology (INST), Hanoi, Vietnam for the purposes of radiation protection and calibrations. The dosimetric quantities of spectral neutron fluence rates and neutron ambient dose equivalent rates have been calculated and presented using the Monte Carlo N-Particle transport code, version 5 (MCNP5) and Bonner sphere spectrometer (BSS) measurements in the combination with MAXED unfolding code. The characterizations of neutron reference fields have been done, complying with the ISO 8529 and 12789 series. The results confirm the neutron calibration capability at the INST in order to fulfill the domestic calibration demands of neutron ambient dose equivalent rate meters.