The formation of nanoporous gold by open circuit dealloying of 100 nm AgAu foils in nitric acid is investigated in situ and in real time by combining synchrotron small angle X-ray scattering (SAXS) and X-ray diffraction (XRD). The time dependence of the dealloying is followed as a function of acid concentration. For all concentrations, several characteristic dealloying stages are observed. Firstly, there is a fast initial dissolution stage with an increase in surface area due to pore and mound formation; this leads to strain in the nanoporous gold that results from an increase in capillary pressure. After dissolution is complete, there is rapid coarsening of the quasi-periodic, pore–ligament morphology. During this later stage, we deduce strong strain anisotropies that can be explained by preferred crystallographic orientation of ligaments. This rapid coarsening stage is followed by a slow coarsening stage where the SAXS patterns, and hence the quasi-periodic morphology, is self-similar in time. There is a strong correlation between the morphology evolution and strain development, which can be explained by capillary forces.