A process for the isolation of particulate polyarylene esters having good thermal stability and hydrolytic stability, which comprises adding to a solution of a polyarylene ester in an organic solvent a poor solvent for the polyarylene ester at least in an amount such that said solution reaches a cloud point, followed by subjecting said mixed solution to an aging treatment whereby the polyarylene ester precipitates as solids, characterized in that said poor solvent is a mixed poor solvent consisting of 5-95% by weight of an aliphatic alcohol with 1-5 carbons and the other poor solvent for the polyarylene ester, the amount of said mixed poor solvent added being within the range of 100-200% by weight of the amount such that said solution reaches the cloud point and not exceeding the amount of said solution.