Display omitted •A non-stationary coherent superposition of the ground and first excited states of LiH and its isotopomers is pumped.•The two states are of opposite polarity and are separated by a small energy gap.•A mass-independent early charge migration is exhibited by all three isotopomers, LiH, LiD, LiT.•The closely similar coherent dynamics of all three isotopomers persists for approximately 2 fs. Charge migration in LiH molecule and its isotopomers LiD and LiT is examined by quantum dynamics including the non-adiabatic effects of nuclear motions. Upon excitation by an ultrafast UV pulse, mass-independent charge migration occurs between the ground and first excited Σ states. The opposite polarity of these states and a relatively small energy gap between them allow the charge to oscillate at early time of the dynamics during 2 fs after the pulse is over. When the nuclei move, a mass-dependent revival of coherence is computed with a period of 80, 107, 123 fs for LiH, LiD, and LiT, respectively.