The solid-state elimination reaction in sodium chloroacetate was studied with in-situ combined small- and wide-angle X-ray scattering (SAXS-WAXS). This reaction leads to sodium chloride cubes (d approximate to 1 mu m) finely dispersed in a matrix of partially crystalline polyglycolide, poly(hydroxyacetic acid). The wide-angle data confirm a single-step reaction without detectable intermediate. The formation of the superstructure of polyglycolide (detectable by SAXS) is delayed compared to the formation of crystalline domains (detectable by WAXS). This is indicated by the intensity of the long period diffraction peak at s = 0.104 nm(-1).