  We investigate the radiation from an inertial scalar particle evolving in a
de Sitter expanding Universe. In the context of scalar QED the process is
generated by the first order term in the perturbation theory expansion of the
S-matrix. The partial transition probability is obtained and analysed, and
soft-photon emission is found to dominate overall. It has been argued that an
inertial particle evolving in dS spacetime loses physical momentum just as a
decelerated particle in Minkowski space does. It is thus expected that an
inertial charge will radiate in a similar way. We investigate the radiated
energy and make a qualitative comparison of the angular distribution of the
energy with the radiation pattern in the latter case.
