A Round Robin Test exercise on magnesium hydride (MgH2) was performed by 14 laboratories with the aim to compare experimental isothermal data such PCI curves, kinetics curves and formation enthalpies together with a basic statistical evaluation of the results. The full hydrogen capacity was found to vary in the range 5.1-6.4 wt.% at 280 degrees C (553 K) and in the range 5.3-6.6 wt.% at 320 degrees C (593 K) (value for 1 MPa hydrogen pressure). The relative standard deviations of 6.9% and 7.2%, respectively, were measured for absorption. The absorption plateau pressure of magnesium hydride varies between 0.08 and 0.14 MPa with an average of 0.10 MPa and a relative standard deviation of 17.3% at 280 degrees C (553 K). At 320 degrees C (593 K) the absorption plateau pressure results fall in the range 0.26-0.45 MPa, with a relative standard deviation of 17.6%. Kinetics curves were affected by much higher data dispersion than the PCI data. The enthalpy of absorption was -75.7 KJ/moleH(2), with a relative standard deviation of 4.4%. The results highlight the importance of well defined measuring and reporting protocols as a base for future standard procedures. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.