Intrinsic viscosities [Î·] of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) solutions have been measured as a function of temperature between 60 and 25Â°C. The solvents were toluene and trichloroethene. In both solvents, the [Î·]-T curve exhibited a point of inflection in the range 45-35Â°. This phenomenon is explained as a conformational transition, which is possibly involved in the nucleation process of the solution crystallization of PPO. Assuming constancy of the coil expansion factor Î±Î· and the solvent draining over the whole temperature interval, a slight increase of characteristic parameter CÎ±, with decreasing temperature has been calculated.