Erbium hydride thin films are grown onto polished, a-axis α Al2O3 (sapphire) substrates by reactive ion beam sputtering and analyzed to determine composition, phase and microstructure. Erbium is sputtered while maintaining a H2 partial pressure of 1.4 ×10−4 Torr. Growth is conducted at several substrate temperatures between 30 and 500°C. Rutherford backscattering spectrometry (RBS) and elastic recoil detection analyses after deposition show that the H/Er areal density ratio is approximately 3:1 for growth temperatures of 30, 150 and 275°C, while for growth above ∼430 °C, the ratio of hydrogen to metal is closer to 2:1. However, x-ray diffraction shows that all films have a cubic metal sublattice structure corresponding to that of ErH2. RBS and Auger electron spectroscopy confirm that sputtered erbium hydride thin films are relatively free of impurities.