Inconel 690 is a nickel-base superalloy which, because of its superior corrosion resistance, is being considered as a substitute for Inconel 600. The composition of Alloy 690 is nominally 30wt.%Cr-10wt.%Fe-0.3wt.%Ti-bal Ni. This alloy is generally used in the thermally treated condition: solution anneal in the range 1030-1120*C for ∼0.07-lh followed by a thermal treatment (∼550-875*C for ∼10h) [1,2]. The purpose of this study is to characterize the microstructure during the post-annealing thermal treatment by scanning/transmission electron microscopy (STEM/TEM). Of particular importance is the identification of precipitates and the documentation of Cr depletion at grain boundaries and precipitates. Specimens were examined in the 1) annealed, and 2) annealed and thermally treated conditions.TEM examination of the annealed alloy revealed that the conventional annealing treatment did not result in the complete dissolution of the M23C6 precipitates. Numerous coarse matrix carbides were visible in the alloy. In addition, notable intergranular precipitation of M23C6. occurred during cooling from the annealing temperature (Fig. 1.).