A series of high molecular weight azoaromatic polyethers was prepared by the reaction of bisphenols with 4,4’-difluoroazobenzene in N-methylpyrrolidinone in the presence of anhydrous potassium carbonate. The activating influence of the aromatic azo group towards nucleophilic displacement reactions was first established by appropriate model compound studies. The polymers were amorphous in nature and tough films could be obtained upon solution casting from chloroform. The azoaromatic polyethers exhibit well defined glass transition temperatures and undergo thermal crosslinking at elevated temperature. Photo-viscosity effects due to cis-trans isomerism of the azo groups were also investigated.