The cold sintering process (CSP) densifies ceramics at muchl ower temperatures than conventional sintering processes.S everal ceramics and composite systems have been successfully densified under cold sintering.F or the grain growth kinetics of zinc oxide,r educed activation energies are shown,and yet the mechanism behind this growth is unknown. Herein, we investigate these mechanisms in more detail with experiments and ReaxFF molecular dynamics simulations.W e investigated the recrystallization of zinc cations under various acidic conditions and found that their adsorption to the surface can be ar ate-limiting factor for cold sintering.O ur studies show that surface hydroxylation in CSP does not inhibit crystallization;i nc ontrast, by creating as urface complex, it creates an orders of magnitude acceleration in surface diffusion, and in turn, accelerates recrystallization.