Second-order non-linear optical (NLO) poly(phenylquinoxalines) with high glass transition temperatures were prepared by reaction of bis(1,2-diketone)chromophore monomer and a tetramine at room temperature. Glass transition temperatures in the range of 187-260 degreesC were obtained. Thin spincoated films of the polymers were corona-poled and analysed by second-harmonic generation (SHG). Second-order susceptibility values d(33)(omega) UP to 114 pm/V were obtained. Poled order stability measurements over a period of 750 h resulted in up to 91% of remaining NLO-response at 125 degreesC. (C) 2005 Elsevier Ltd. All rights reserved.