Novel proton-conducting polymer electrolyte membranes have been prepared from bacterial cellulose by incorporation of phosphoric acid (H3PO4/BC) and phytic acid (PA/BC). H3PO4 and PA were doped by immersing the BC membranes directly in the aqueous solution of H3PO4 and PA, respectively. Characterizations by FT-IR, TG, TS and AC conductivity measurements were carried out on the membrane electrolytes consisting of different H3PO4 or PA doping level. The ionic conductivity showed a sensitive variation with the concentration of the acid in the doping solution through the changes in the contents of acid and water in the membranes. Maximum conductivities up to 0.08 S cm-1 at 20oC and 0.11 S cm -1 at 80oC were obtained for BC membranes doped from H3PO4 concentration of 6.0 mol L-1 and, 0.05 S cm-1 at 20oC and 0.09 S cm -1 at 60oC were obtained for BC membranes doped from PA concentration of 1.6 mol L-1. These types of proton-conducting membranes share not only the good mechanical properties but also the thermal stability. The temperature dependences of the conductivity follows the Arrhenius relationship at a temperature range from 20 to 80oC and, the apparent activation energies (Ea) for proton conduction were found to be 4.02 kJ mol-1 for H3PO4/BC membrane and 11.29 kJ mol-1 for PA/BC membrane, respectively. In particular, the membrane electrode assembly fabricated with H3PO4/BC and PA/BC membranes reached the initial power densities of 17.9 mW cm-2 and 23.0 mW cm-2, which are much higher than those reported in literatures in a real H2/O2 fuel cell at 25oC.