Symbol θ. The unique temperature at which the attractions and repulsions of a polymer in a solution cancel each other. A polymer solution at the Flory temperature is called a theta (θ) solution.

At the Flory temperature the virial coefficient B, associated with the excluded volume of the polymer, is zero, which results in the polymer chain behaving almost ideally.

This enables the theory of polymer solutions at the Flory temperature to provide a more accurate description of events than for polymer solutions at other temperatures, even if the polymer solution is concentrated.

It was named after the US physicist Paul Flory (1910-85).