Nonlinear optical poly(ether imides) with an adequate thermal stability has been synthesized by direct coupling of hydroxy poly(ether imides) and NLO chromophores with a quantitative yield. The resultant amorphous NLO poly(ether imides) exhibited good solubility in common organic solvents, providing optical-quality thin films by spin coating. The glass transition temperatures of the polymers are at around 180 degrees C. The electrooptic coefficients (r(33), @1.3 mu m) of PEI-DR1 was 12.3 pm/V with an electrical poling field of 100 V/mu m and it decayed about 10 % over 10 months at 90 degrees C under atmospheric conditions.