A measurement of the top-antitop production charge asymmetry A C 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 tt event topology. After background subtraction, a Bayesian unfolding procedure is performed to correct for acceptance and detector effects. The measured value of A C is AC=−0.019±0.028 (stat.)±0.024 (syst.) , consistent with the prediction from the MC@NLO Monte Carlo generator of A C =0.006±0.002. Measurements of A C in two ranges of invariant mass of the top-antitop pair are also shown.