Polymethacrylate and polycondensated polymers based on chromophores containing the s-triazolo[3,4-b]-thiadiazole heterocycle were synthesized. Chromophore and polymer preparations are described. Second order NLO measurements are reported for polymers and for one functionalized chromophore. The maximum value of second harmonic generation coefficient (d(33)) measured is 11.5 pm/V at incident laser wavelength of 1368 nm. For the most active polymer, 85% of the initial d(33) value is retained after 27 days at 80 degrees C. (C) 2007 Elsevier Ltd. All rights reserved.