After the discovery of the Higgs Boson, one of the main focus of the LHC experiments became the search for beyond standard model physics. As the name suggests, it includes a wide range of physics scenarios, like extra dimensions, supersymmetry, dark matter, and many others. Dark Matter (DM), as cosmological observations suggests, is supposed to be a kind of matter that do not have electric charge and do not interact with strong force. At the LHC (Large Hadron Collider), and more specifically at the CMS (Compact Muon Solenoid) experiment, the search is performed using many theoretical frameworks, like DM production in SUSY decays, simplified models and DM production in the decay of a Higgs Boson, just to mention a few. Since this kind of matter do not have electric nor strong charge, the detector can not record their production but it is possible to infer its existence by analysing events with missing transverse energy (MET). Simplified models are a good way to do a general search. It consists in production of DM through new mediators, which couples the DM with usual matter, and needs few free parameters (DM and mediator masses, spin and couplings). This work present a Monte Carlo simulation study of the production of events with a final state photon with large transverse momentum and large missing transverse energy at CMS. This is a sensitive probe of Dark Matter since this signature has the advantage of being identifiable with high efficiency.