Electromagnetic physics objects commissioning with first LHC data

In this paper we describe the use of the data from the first proton-proton collisions recorded by the CMS detector, at center of mass energy of 900 GeV, to commission the reconstruction of electron and photon physics objects. First comparisons between the data and the simulation of various key ingredients for the reconstruction and identification of electrons and photons are shown. There is good agreement, suggesting a good modeling of the response of the inner tracker and the calorimeters.