Fly ash obtained from Toshkey project, which in turn was delivered from France, is a valuable source of many oxides such as SiO2, Al2O3, Fe2O3, CaO and MgO. These oxides can provide a useful preliminary source for the glass formation. Glass of the system 10Li(2)O-90B(2)O(3) (wt.%) has been prepared. The progressive addition of fly ash to this type of glass was made to study its effect on the chemical and physical properties of the parent glass. Room temperature ultrasonic measurements were performed by pulse-echo method. The density of the prepared samples was measured to justify the packing arrangements of the constituent oxides. The variations in the density and the ultrasonic velocity of the prepared samples containing progressive fly ash content were correlated and discussed. The values of elastic moduli (Young's modulus, bulk modulus and shear modulus) and Poisson's ratio were compared with those theoretically calculated in terms of Makishima-Mackenzie model and a model proposed by Rocherulle et al. [J. Rocherulle, C. Ecolivet, M. Poulain, P. Verdier, Y. Laurent, J. Non-Cryst. Solids 108 (1989) 187]. (c) 2005 Elsevier B.V. All rights reserved.