Many novel polymer electrolyte membranes were found to replace the Nafion membrane for using in direct methanol fuel cell (DMFC), in order to solve the problem offuel crossover (methanol crossover) in DMFC and also to reduce the cost production of solid electrolyte. Here we found the synthesis of copolymer membrane using the acrylonitrile and 2-acrylamide-2-methyl propane sulfonic acid with DMF as a solvent. The copolymer membrane has a sulfonate to transfer a proton (H+) in fuel cell system. In this result we found that permeability ofthis copolymer will decrease during the addition of supporting electrolyte in various methanol concentrations. The surface of membranes was analyzed using SEM. These results must be usefully as polymer electrolyte to solve the problem of water control in high temperature offuel cell and also in direct methanol fuel cell. Key words: Fuel cell; methanol crossover; koefisien difusi; proton exchange membrane. Eniya Listiani DewP, Dani Endar Purwanto2, Dora Olivia2 dan RochmadF IPusat Pengkajian dan Penerapan Teknologi Material (P3TM) - BPPT Gd.IJ, Lt. 22, Jl. M H Thamrin 8 Jakarta 10340 2Laboratorium Teknologi Tinggi Polimer, Jurusan Teknik Kimia, UGM Jl. Grafika 2, Yogyakarta 55281