In order to develop red emitting phosphors for W-LEDs, a series of Eu3+ (2, 4, 6 and 8 mol%) doped potassium magnesium borate (KMB) phosphors were prepared using a solid state reaction technique at 700 oC. The structure, morphology, optical and luminescent properties of prepared phosphors were investigated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), absorption spectrometer (UV-Vis) and spectrofluorimeter. In accordance with the XRD analysis, the undoped and Eu3+ doped phosphor samples have a single phase cubic crystal structure with P213 space group. Based on the FTIR studies, all of the synthesised phosphor samples have metallic and Bo3 bonds. The absorption bands in the UV-Vis-NIR region were identified and the energy band gap values were evaluated using the absorption spectra