Thermal stability and passivation properties of Ba-induced incorporation phase on Ge(001) under ultra-high vacuum (UHV) conditions are investigated using scanning tunneling microscope (STM). We show that the generic c(4 x 2) reconstruction of Ge(001) can be easily reinstated in the Ba/Ge(001) sample, stored for more than 40 days under UHV and room temperature conditions, just by thermal annealing at 1070 K under UHV. Our data implies that this process occurs predominantly via temperature assisted desorption of Ba adatoms from the on-top phase formed as an intermediate during annealing process and known to preserve the c(4 x 2) reconstruction of Ge(001). The reported results indicate that the Ba-induced incorporated phase on Ge(001) is very effective in protecting the Ge(001) substrate against destructive adsorption of residual gases and can be utilized for long-term, non-destructive Ge sample storage under UHV conditions. (C) 2017 Elsevier B.V. All rights reserved.