We study a relativistic fluid jet driven by radiation from accretion disc
around a non-rotating black hole. We compute the radiative moments with
full special relativistic transformations. We show that the terminal speed
of jets increases with the mass accretion rates, synchrotron emission of the
accretion disc and reduction of proton fraction of the flow composition. To
obtain relativistic terminal velocities of jets, both thermal and radiative driv-
ing are important. We show for very high accretion rates and pair dominated
flow, jets around super massive black holes are truly ultra-relativistic, while
for jets around stellar mass black holes, terminal Lorentz factor of about 10
is achievable.