We report on the measurement of the formation of gamma-ZrH during in situ gaseous charging. The measurements were undertaken using high-energy synchrotron X-ray diffraction. Experimental observation shows that gamma-ZrH can form at 180 degrees C from a mixture of alpha+delta while dehydrogenating at slow cooling rates. The observation is further supported by ex situ laboratory X-ray diffraction on deuterated Zr powder that has undergone a similar heat-treatment cycle. The crystal structure of gamma-ZrH refinement agrees with the reported P4(2)/n structure found in the literature. (C) 2016 Elsevier B.V. All rights reserved.