The glass forming limit by substitution of CdS for CdO in a CdO-B(2)0(3) glass was determined by chemical analysis. When x CdS-(60-x)CdO-40B(2)0(3) nominal mixtures in weight ratio were heated at 1100°C in flowing nitrogen gas for 1/2 hour, about 40~50% of mixed CdS and 10-15% of the mixed CdS were evaporated. The limit of nominal composition for glass forming was 10CdS-50CdO-40B(2)0(3) and the corresponding virtual composition after the above heat treatment was found to be 4.9CdS-46.4CdO-48.7B(2)O(3). Further addition of CdS made the melt devitrefied with CdS precipitation. D.C. conductivity measurements revealed that the current density was not linear with respect to the applied voltage, but the resistivity ranged around 10(12)Ω･cm for 4.1CdS-48.8CdO-47.1B(2)O(3) (virtual composition) glass and around 10(11.5)Ω·cm for 4.9CdS-46.4CdO-48.7B(2)O(3) glass. These sulphur containing glasses did not show photoconduction, although CdS-precipitated materials showed slight photoconductivity when disposed in ultra violet radiation. Apparent dielectric constant and tan 8 were also measured as a function of frequency, revealing a moderate dispersion in the CdS-precipitated glasses.