Aging solution-treated Cu-Ti alloys in a hydrogen atmosphere significantly improved their electrical conductivity without degradation of the mechanical strength, compared to conventionally aged alloys. In this study, the influence of prior deformation on the mechanical and electrical properties of Cu-4.2 at.% Ti alloys aged in a hydrogen atmosphere was examined. The Vickers hardness of the solution-treated specimen increased from 127 kgf/mm2 to 265 kgf/mm2 by aging at 673 K for 180 h in a hydrogen atmosphere of 0.8 MPa, while that of the deformed specimen achieved a maximum of approximately 280 kgf/mm2 by aging for 100 h in the same atmosphere. Prior deformation resulted in a more rapid increase in conductivity during aging than that without deformation. The conductivity at the peak-hardness of the deformed specimen was 22% IACS (International Annealed Copper Standard), which exceeded that for the solution-treated specimen. Thus, prior deformation assisted in a significant improvement of the mechanical and electrical properties during aging in a hydrogen atmosphere.