Effects of tritium content on crystal lattice, He-3 retention and structure evolution during aging of Ti tritides were investigated using X-ray diffraction, together with analysis of He-3 release. Phase transformation and lattice parameters of the Ti tritides varied apparently depending on tritium stoichiometry. Initial tritium content in the Ti tritides showed significant effects on He-3 retention due to the existence of alpha + delta phase boundaries and lattice symmetry in the Ti tritide. The critical contents of He-3 release in the alpha + delta phase region and epsilon phase region were found to be smaller than that in the delta phase region. Variation of crystal lattice structures of alpha + delta, delta and epsilon phases in the Ti tritides has been investigated, and evolution of He-3 during aging is mainly governed by the finite defects of self-interstitial atoms, dislocation loops, He-3 bubbles, and dislocations created by formation and growth of He-3 bubbles. In the alpha + delta two phase region, the phase boundaries played an important role to accumulate He-3 bubbles and cause inter-bubble fracture. In the epsilon phase region, a preferred condensation of finite defects in basal plane of Ti tritide lattice and formation of a dislocation network were identified. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.