Novel NLO azo-based chromophores containing strong electron-withdrawing groups and benzene or thiazole moiety as conjugated bridges were synthesized and characterized. beta values were measured by HRS method, they are in the range of 238 - 1459 x 10(-30) esu at the fundamental wavelength of 800 nm. For chromopheres 3 and 4, beta values at the fundamental wavelength of 1064 nm were also measured, they are 1575 x 10(-30) esu and 935 x 10(-30) esu, respectively. Thermal stabilities for these chromophores are reported. We also discuss the effects of different acceptors and conjugating moieties on beta. (C) 2004 Kluwer Academic Publishers.