A composite proton conductive membrane, comprising an inorganic filler having covalently bonded acidic functional groups and a high surface area of at least 150 m2/g; and a water insoluble ionically conductive polymer. This membrane provides advantages over traditional polymeric proton conductive membranes for redox flow battery, fuel cell, and electrolysis applications include: 1) enhanced proton conductivity/permeance due to the formation of additional nanochannels for proton conducting; 2) improved proton/electrolyte selectivity for redox flow battery application; 3) reduced membrane swelling and gas or electrolyte crossover; 4) improved chemical stability; 5) increased cell operation time with stable performance, and 6) reduced membrane cost.