Abstract: A monolithic electrode structure for use in electrochemical flow cells is presented. The monolithic electrode structure includes a dense region with embedded flow channels that provides functionality of a flow field layer and a porous region that provides combined functionalities of gas diffusion and catalyst layers. The monolithic electrode structure is additively fabricated to include regions of different porosities/densities. A material of the monolithic electrode structure is a pure metal that is a catalyst for a targeted electrochemical reaction, or an alloy that contains such pure metal. Porosity of the porous region is adjusted to allow flow of liquid, such as water, towards or away from an active surface of the electrode. According to one aspect, porosity is adjusted by adjusting the pore size that make the porous region. According to another aspect, the dense region contains cooling channels for cooling of the electrode.