  The existence of dark energy is essential to explain the cosmic accelerated
expansion. We consider a homogenous interacting tachyonic scalar field as a
possible candidate for the dynamical dark energy. The interaction between the
tachyonic field and matter can be gauged to be linear in the energy density of
matter (or the tachyonic field) and Hubble's parameter. We estimate the rate of
expansion, the age of the universe, the evolution of energy density of matter
and tachyonic field, and the coupling strength of the interaction for a
spatially flat ($k=0$) universe. We observed that the upper limit of coupling
strength is 1, and it is the same whether the interaction term depends on the
energy density of matter or the energy density of tachyonic scalar field.
