N-doped graphene (NG) was synthesized by annealing reduced graphene oxide (RGO) in an ammonia atmosphere. The dependence of the nitrogen content on the annealing temperature and the type of doping of NG were investigated. The photoluminescence (PL) properties of the RGO and NG samples were studied. The results show that RGO exhibits strong ultraviolet (UV) PL at 367 nm. The PL of RGO can be quenched by doping it with N and the quenching efficiency depends on the pyridine N content.