Doping of bismuth lead oxyfluorides by silica (30 at.%) makes it possible to stabilize a large vitreous domain. The presented study relates to the stability of the vitreous phase and the variation of conductivity versus temperature, as well as composition. DTA heating analyses evidenced the temperature of vitreous transition followed by the material recrystallization. The crystallized phase was identified by high temperature Guinier Lenne pattern. The best conductivity, about 3 x 10(-3) Scm(-1) at 220 degrees C, was obtained for the fluorine richest material. (C) 2009 Elsevier B.V. All rights reserved.