[en] The sodium borosilicate system 30 Na_2O-(70-X)(1/7 SiO_2:6/7B_2O_3)-X Sm_2O_3 with X varying from 0, 0.5,1,1.5 and 2 mol % was prepared by conventional melt quench technique. Impedance measurement was done in the frequency range 20 MHz to 2 mHz in the temperature range 150 to 400°C. It is observed that affects the electrical conductivity, density, molar volume and glass transition temperature varies with the addition of samarium oxide. The results have been explained on the basis of variation in number of bridging oxygen (BOs) and non bridging oxygen (NBOs). Variation of dielectric constant and dielectric loss is discussed with the addition of Sm_2O_3