The ATLAS experiment has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at s√=7  TeV. The full data set acquired in 2010 is used, corresponding to an integrated luminosity of 37  pb−1. The background, consisting of hadronic jets and isolated electrons, is estimated with fully data-driven techniques and subtracted. The differential cross sections, as functions of the di-photon mass (mγγ), total transverse momentum (pT,γγ), and azimuthal separation (Δϕγγ), are presented and compared to the predictions of next-to-leading-order QCD.