Polymer Electrolyte Membrane (Pem) Fuel Cells - Also Called Proton Exchange Membrane Fuel Cells - Deliver High Power Density And Offer The Advantages Of Low Weight And Volume, Compared To Other Fuel Cells. Pem Fuel Cells Use A Solid Polymer As An Electrolyte And Operate At Relatively Low Temperatures, Around 80°C. Low Temperature Operation Allows Them To Start Quickly (Less Warm-Up Time) And Results In Less Wear On System Components, Resulting In Better Durability. The Currently Used Fluorinated Membranes In Pem Fuel Cells Are Very Expensive And Are Of Environmental Concern Due To The Fluorine Chemistry. Keeping In View The Above Concerns, Composite Membranes Appear To Be A Promising Alternative To Commercially Available Perfluorosulfonic Acid Membranes. This Work Deals With The Preparation And Characterization Of Composite Pems Using Environmentally Benign Materials For Fuel Cell Application. Series Of Composite Membranes Were Prepared Using Poly (Vinyl Alcohol) And Its Copolymer As Polymer Matrix And Heteropoly Acids As Proton Conducting Dopant. The Heteropoly Acids Are Very Attractive Inorganic Fillers For The Preparation Of Composite Pems. The Prepared Composite Membranes Were Chemically Crosslinked To Optimize Their Properties. The Prepared Crosslinked Composite Pems Were Characterized By Several Characterization Techniques To Determine Their Feasibility For Fuel Cell Application. The Cost-Benefit Performance Analysis Of The Prepared Composite Pems Was Also Carried Out To Compare Their Properties To The Commercially Available Nafion Pem. Promising Results Were Obtained For The Prepared Composite Pems And These Membranes Appear To Be Good Candidates As An Alternative Pem For Direct Methanol Fuel Cell Applications.