Hugo M. Rietveld (7 March 1932 - 16 July 2016 ) was a Dutch crystallographer who is famous for his publication on the full profile refinement method in powder diffraction, which became later known as the Rietveld refinement method. The method is used for the characterisation of crystalline materials from powder diffraction data. The Rietveld refinement uses a least squares approach to refine a theoretical line profile (calculated from a known or postulated crystal structure) until it matches the measured profile. The introduction of this technique which used the full profile instead of individual reflections was a significant step forward in the diffraction analysis of powder samples.
After completing Grammar School in the Netherlands he moved to Australia and studied physics at the University of Western Australia in Perth. In 1964 he obtained his PhD degree with a thesis entitled "The Structure of p-Diphenylbenzene and Other Compounds", a single crystal neutron and X-ray diffraction study. This investigation was the first single crystal neutron diffraction study in Australia and was conducted at the nuclear reactor, HIFAR, in Sydney.
In 1964 he became a research officer at the Netherlands Energy Research Foundation ECN in Petten, where he worked together with Bert Loopstra and Bob van Laar on the structure solution and refinement of uranates and other ceramic compounds using neutron powder diffraction. In 1967 he implemented the full profile refinement method in a computer program, which he published in his 1969 citation classic. This innovation, however, was only slowly adopted by the community, and so Rietveld in 1974 chose to become head of the library department at Petten. He stayed at ECN until he retired in 1992.