An ultra-thin anion exchange membrane incorporates functional additives to provide improved water management. Without the functional additives the ultra-thin membrane may have high cross-over and not be effective for many applications. A composite anion exchange membrane includes a porous scaffold support such as a porous polymer. The anion exchange polymer may be coupled to the porous scaffold, such as by being imbibed into the pores of the porous scaffold. The functional additives may contribute to increase water production, water retention, back-diffusion and reduce the gas crossover. A functional additive may include a reactive species, including a catalyst that reacts with oxygen or hydrogen, a plasticizer, a hygroscopic material and/or a radical scavenger.