CMS Electromagnetic Calorimeter status and performance with the first LHC collisions

The Electromagnetic Calorimeter (ECAL) of the Compact Muon Solenoid (CMS) detector will play a crucial role in new physics searches at the Large Hadron Collider (LHC) as well as in Standard Model precision measurements. The first LHC beams have been used to finalize the commissioning of ECAL read-out and trigger. The precision of the inter-channel synchronization and calibration has been verified and improved with in-situ data. The quality of the offline data reconstruction has been investigated with physics signals, in particular with di-photon states. A review of the CMS ECAL detector status and performance is presented in this note.