  We present an estimation of the strong coupling constant alphas(MZ) using,
for the first time, the production of prompt photon process in proton-proton
collisions at the LHC. ATLAS measurements of the inclusive isolated prompt
photon cross section at 7 TeV are exploited. Both theoretical and experimental
uncertainties are estimated and the strong coupling constant has been
determined to be alphas(MZ)= 0.1183 +- 0.0038, to NLO accuracy.
