ositron annihilation lifetime spectra have been measured for the samples of Na2O-B2O3 melt. B2O3
SiO2. V2O5 and Na2O-TiO2 melt during sharp cooling with a cooling rate>180K.s 1.The results show a quite well linear relation between optical basicity A and the first component τ1 of the lifetime spectra for non-transition metal oxides: A= 0.173 (1/ τ1) +0.060.With this relationship and τ1measured by PA the A values for ZnO.TiO2 and V2O5.are obtained to be 1.00. 0.63 and 0.75 respectively