  We study the impact of electroweak radiative corrections on direct production
of photons with high transverse momenta at hadron colliders. Analytic results
for the weak one-loop corrections to the parton scattering reaction $\bar q q
\to \gamma g$ and its crossed variants are presented. For the high-energy
region, where the corrections are strongly enhanced by logarithms of $\hat
s/M_W^2$, we derive simple asymptotic expressions which approximate the exact
one-loop results with high precision. The dominant two-loop electroweak
contributions are also calculated. Numerical results are presented for the LHC
and the Tevatron. The corrections are negative and their size increases with
transverse momentum. For the LHC, where transverse momenta of 2 TeV or more can
be reached, the size of the one- and two-loop effects amounts up to -17% and
+3%, respectively. At the Tevatron, with transverse momenta up to 400 GeV, the
one-loop corrections do not exceed -4% and the two-loop effects are negligible.
Finally we compare the cross sections for hadronic production of photons and Z
bosons and find that the electroweak corrections have an important impact on
their ratio.
