The dimensions of linear polymer chains are scaled to their molar mass (M) as R = kM(alpha) with alpha = 1/2 and 3/5 in a theta and an athermal solvent, respectively. In a good solvent, both k and alpha are a function of the solvent quality and chain length range A high-temperature laser light-scattering spectrometer was used to measure the average radius of gyration (< R-g >) and hydrodynamic radius (< R-h >) of a set of narrowly distributed linear polystyrene chains in decalin over a wide temperature range k and alpha in the scaling experimentally varying with T over a chain length range was analyzed The results reveal that for < R-g >, alpha = 0 59 0.09exp(-tau/0 066) and k = 0 60 tau(2 alpha-1), reasonably agreeing with the thermal blob theory For < R-h >, alpha = 0.59 0 09exp(-tau/0.106). but k deviates from the relationship of k proportional to tau(2 alpha-1), reflecting that the hydrodynamic interaction and chain draining are not considered in the thermal blob theory. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.