Phosphors are substances that exhibit light due to fluorescence or phosphorescence. Y2Si3O3N4 and Lu2Si3O3N4 were doped with Ce3+ in 2 mol % using a solid state reaction method. Ce3+ luminescence was studied in both systems. These phosphors can be paired with commercial light emitting diodes (LEDs) to produce white light. LEDs are very efficient and helps battle global warming due to less energy consumption. Oxynitride phosphors are known to have great thermal and chemical stability because of the tetrahedrons share corners giving great stability. We optimized the flux; heating time and temperature need to synthesize the two systems. Characterization of both systems was done with X’Pert X-Ray Diffraction (XRD) to obtain its crystal structure. We used Rietveld Refinement to refine its crystal structure and Perkin Elmer LS 55 Fluorimeter to obtain its luminescence characteristics. We found Y2Si3O3N4 to be emitted at 471 nm when excited with blue light. Although we could not synthesize the Lu2Si3O3N4:Ce3+ system which may be due to Lutetium (Lu) having a smaller ionic radius than Cerium (Ce).