Dealloying of multicomponent metals is known to generate highly topologically complex structures with micron- or nano-scale ligaments and voids. Some examples of porous metals synthesis via dealloying include aqueous solution dealloying (e.g. Ag dealloying from AuAg in acid), liquid metal dealloying (e.g. Ti dealloying from TaTi in liquid Cu), and, more recently, molten salt dealloying (e.g. Cr dealloying from NiCr in molten salt). Dealloyed nanoporous metals have been shown to possess remarkable catalytic properties, large capacitance, and high mechanical strength when compared to their bulk counterparts. However, these desirable properties can be deleteriously affected by the presence of grain boundaries in the metal, which are known to affect the ligament size and connectivity of these dealloyed structures. Although the microstructure of the solid alloy precursor is expected to play an important role in this dealloying, the detailed mechanisms underlying how features such as grain boundaries may alter this process are less understood. It is critical to understand these mechanisms of grain boundary dealloying corrosion to optimize nanoporous materials synthesis. In this work, Nathan Bieberdorf et al. from the Department of Materials Science and Engineering, University of California, Berkeley, employed a multi-phase field model to study the microstructural evolution of an alloy undergoing liquid dealloying, specifically considering the role of grain boundaries. A semi-implicit time-stepping algorithm using spectral methods was implemented, which enables simulating large 2D and 3D domains over long time scales while still maintaining a realistic interfacial thickness. Simulations revealed a mechanism of coupled grain–boundary migration to maintain equilibrium contact angles with the topologically complex solid–liquid interface, which locally accelerates diffusion-coupled growth of a liquid channel into the precursor. This mechanism asymmetrically disrupts the ligament connectivity of the dealloyed structure in qualitative agreement with published experimental observations. The grain boundary migration-assisted corrosion channels form even for precursors with small amounts of the dissolving alloy species, below the parting limit. The activation of this grain boundary dealloying mechanism depends strongly on grain boundary mobility. The multi-phase field model proposed in this work could be applied towards a wide range of topologically complex evolving nano-scale structures.