The synthesis of O-17-enriched alpha-tellurite (alpha-TeO2) is described. TeO2 is obtained stochiometrically by the reaction of tellurium isopropoxide with O-17-enriched H2O. The reaction is mild and simple and opens the field of tellurite-based ceramics to O-17 nuclear magnetic resonance spectroscopy. We also report the first 1 70 nuclear magnetic resonance spectra of alpha-TeO2 and Na2TeO3. Their isotropic chemical shifts, delta(iso), are 180 ppm and 158 ppm, respectively, and their quadrupolar coupling parameters are C-Q = 7.48 MHz and eta = 0.43 for alpha-TeO2, and CQ = 6.63 MHz and eta = 0.33. By using extended Huckel tight binding calculations, we interpret the chemical shifts of tetravalent inorganic oxide network formers (SiO2, GeO2, and TeO2) in terms of the local paramagnetic shielding effect. We also show that this is the predominant effect in determining the chemical shifts of non-bridging oxide sites in this type of network.