New red sesquioxide phosphor, Eu(3+)doped (Y0.5La0.5)(2)O-3, was synthesized in the form of nanocrystalline powder with excellent structural ordering in cubic bixbyite-type, and with nanoparticle sizes ranging between 10 and 20 nm. Photoluminescence measurements show strong, Eu3+ characteristic, red emission (x = 0.66 and y = 0.34 CIE color coordinates) with an average D-5(0) emission lifetime of about 1.3 ms. Maximum splitting of the F-7(1) manifold of the Eu3+ ion emission behaves in a way directly proportional to the crystal field strength parameter, and experimental results show perfect agreement with theoretical values for pure cubic sesquioxides. This could be used as an indicator of complete dissolution of Y2O3 and La2O3, showing that (Y0.5La0.5)(2)O-3:Eu3+ behaves as a new bixbyite structure oxide, M2O3, where M acts as an ion having average ionic radius of constituting Y3+ and La3+. Emission properties of this new phosphor were documented with detailed assignments of Eu3+ energy levels at 10 K and at room temperature. Second order crystal field parameters were found to be B-20 = -66 cm(-1) and B-22 = -665 cm(-1) at 10 K and B-20 = -78 cm(-1) and B-22 = -602 cm(-1) at room temperature, while for the crystal field strength the value of 1495 cm(-1) was calculated at 10 K and 1355 cm(-1) at room temperature.