AbstractThe influence of different annealing treatments has been investigated on the stability of the Electro‐Optic coefficient in a poled DANS (4‐dimethylamino‐4′‐nitrostilbene) sidechain polymer, which was poled near its Tg‐onset of 140°C. The annealing treatments and the EO relaxation experiments were performed at 120°C. The EO stability can be significantly increased both by an annealing treatmentafterpoling and by annealingbeforepoling. This latter effect is concluded from the reduction of the EO relaxation rates in successive relaxation cycles performed in the same polymer sample ‐ completely depoled and repoled in between the cycles. The effect from the different annealing treatments on the time‐dependence of the EO relaxation process is different and is analyzed in terms of a Debye‐like model with a single, time‐dependent Debye relaxation time r(t)=ri+C. t3. The time‐dependence ofrand the observed effects from annealing are attributed to the parallel relaxation pro