Hydrogen absorption and desorption often limits a material's application. For titanium, hydrogen absorption kinetics determine its suitability for tritium storage, tritium gettering, and vacuum pump applications. This study examines the absolute rate theory energy surface which molecular hydrogen gas encounters as it is absorbed into alpha-phase titanium. This results in useful new predictions for hydrogen absorption rates, desorption rates, and surface coverages on titanium. The only energy surface which is consistent with observed activation and absorption enthalpies, while predicting all absorption/desorption rate data, is found to contain a new activation barrier. Accuracy is within a factor of 3.6 for two surface preparations and temperatures between 250 and 500 °C. © 1988 The Metallurgical Society of AIME.