A liquid/gas diffusion layer in a proton exchange membrane electrolyzer cell is located between the catalyst layer and flow field/current distributors, which is expected to transport electrons, heat, and reactants/products to and from the catalyst layers. In addition, conventional materials, which are typically used in PEM fuel cells, are unsuitable due to the high ohmic potential and highly oxidative environment of the oxygen electrode. In this study, a set of well-tunable and titanium thin-film liquid/gas diffusion layer with different thicknesses and porosities are designed and fabricated by using photolithography and mask-patterned wet etching techniques. The effect of mask pore size as well as different etchants on the etch rate and pore morphology of titanium is investigated. Ex-situ analysis is also performed to characterize the morphological features of the liquid/gas diffusion layer post etching. From the results of the fabrication and analysis, new methods for the fabrication of well-tunable thin film liquid/gas diffusion layers is detailed.