We report a novel method of temperature gradient interaction h.p.l.c. for the characterization of molecular weight distribution of macromolecules. A very fine and reproducible control of interaction between polymer chains and the packing material can be achieved by altering the column temperature. A mixture of 10 polystyrene standard samples (molecular weight range : 1700-2890 000) of narrow molecular weight distribution are analysed by this method. Near complete separation down to the baseline is achieved with the use of a single C18 bonded silica column. This method is thus proven to provide a much superior resolution to the conventional size exclusion chromatography.