Abstract: The transitions of bisphenol A and phenolphthalein oligo-polysulfones were investigated by DSC. It is found that for both the oligomers, after proper heat-treatment, two more transitions, lower and higher than their T_g,appeared on their DSC curves. It might be reasonable to suggest that these two transitions be due to the disordering of loc 1 short and long range order of molecular arrangements respectively. Equations for linear relationship between T_g and Mn for both the oligomers are given in the paper.