The invention relates to a method for large scale manufacturing of polymeric micro fuel cells using a metallic mold. The method includes creating a Gaussian-shaped channel on a first substrate using a laser; sputtering a metallic seed layer over the first substrate using a first metal; electroplating a second metal over the seed layer to create a negative mold; releasing the negative mold from the first substrate; fabricating a plurality of second substrates, each having a Gaussian-shaped channel, and using the negative mold to fabricate multiple fuel cells. The method provides lower cost and greater flexibility as compared with conventional ablation and etching processes of manufacturing of polymeric micro fuel cells.