The luminescence of lanthanides elements in specially europium have a wide variety of applications including phosphors for fluorescents lighting, display monitors, analytical sensors and immunology applications. This review summarizes a brief history of the discovery, purifications, of the compounds more representative, and the spectroscopy studies responsible of the radiative and non-radiative transitions of the 4f electrons in europium ions since that from they it is determine their optical properties. Europium have its greatest use as a phosphor activator and actually the development of these materials are directed (1) in the doped in diverse matrices (inorganic compounds) known as phosphors, (2) in the synthesis of europium complexes with the organic ligands (ß-diketonate complexes) and (3) europium based organic-inorganic hybrid materials, all they receive attention with relation to preparation, optical properties and potential technological applications in the development and improvement of diverse optical or photonic devices. © 2011 Nova Science Publishers, Inc. All rights reserved.