The sol-gel chemistry route has successfully been used to prepare samples of LnP5O14 (Ln = La, Gd) pentaphosphates from lanthanides chlorides and phosphorous pentoxide dissolved in isopropanol. Crystallized powders of single phase were obtained after calcination of gels at 350 °C. The structural characterizations of materials were investigated by means of X-ray diffraction as well as infrared and Raman spectroscopies, whereas their thermal behavior has been studied by differential thermal analyse and thermogravimetric analyses. Powders morphology was analyzed by means of scanning electron microscopy and laser granulometry. The photoluminescence properties of the Eu3+ ions in sol-gel derived LaP5O14 and GdP5O14 samples were investigated and compared with homologous samples synthesized by the conventional solid state reaction.