A measurement of the top-antitop production charge asymmetry <i>A_C</i> is presented using data corresponding to an integrated luminosity of 1.04 fb⁻¹ of pp collisions at √s = 7 TeV collected by the ATLAS detector at the LHC. Events are selected with a single lepton (electron or muon), missing transverse momentum and at least four jets of which at least one jet is identified as coming from a b-quark. A kinematic fit is used to reconstruct the t ̄t event topology. After background subtraction, a Bayesian unfolding procedure is performed to correct for acceptance and detector effects. The measured value of <i>A_C</i> is <i>A_C</i> = −0.019±0.028 (stat.)±0.024 (syst.), consistent with the prediction from the MC@NLO Monte Carlo generator of <i>A_C</i> = 0.006 ± 0.002. Measurements of <i>A_C</i> in two ranges of invariant mass of the top-antitop pair are also shown.Facultad de Ciencias Exactas