The effect of Bi,O, on the glass transition temperature, electrical conductivity and structure of LiBO, glass has been investigated. r, vs. composition curve shows three different linear regions, while there is an overall decrease in T, with the increase in B&O, content. The slope of these three straight lines is in a decreasing order. These results are interpreted in terms of the increase in the number of non-bridging oxygen atoms, substitution of Bi-0 bond in place of B-O bond and change in Li' ion concentration. The conductivity vs. composition curve exhibits two maxima which are interpreted in terms of the structural modification effect of B&O, on LiBO, network and mixed-former effect, respectively. Results obtained from the XPS studies of the samples of composition x 5 0.005, have shown that the number of non-bridging oxygen atoms from B-O bond increases with the increase in B&O, content. It has a maximum value at n = 0.003 where the conductivity has also exhibited a maximum value. Further increase of B&O, content causes decrease in it. For higher Bi,O, content (x > O.OOS), 0 1s spectra of B&O, has been separated out from that of B,O,. Bismuth ions have been substituted for boron ions as network former ions.