The performance and stability of PTFE/NAfion/Silicate composite membranes (PNS membrane) were studied at low and medium operating temperatures with different humidity, and compared with the Nafion 112 membrabes at the same conditions. The PNS membrane was prepared by impregnation of PTFE/Nafion composite membrane via sol-fel process with TEOS (tetraethoxysilane). When operated cell at low temperature of 60 degrees C with 100% R.H. humidified H(2)/O(2) gases, the PNS membrane performs better than NAfion 112, with 1.0. and 0.1 W/cm(2), respectively. When operated cell at 60 degrees C with 37% R.H. humidified gases, the discharge stability of PNS membrane is stable than that of Nafion 112, this is due to that temperature varied 90, 100, and 110 degrees C, with 20 psig back pressure, their relative humidities were 67, 48 and 33%, respectively. The stability of discharge current remains constant except in the case of cell temperature at 110 degrees C, which is resulted as the membrane dehydration. On the other hand, the NAfion 112 cannot operate at low humidity due to adsorbed water inside the membrane and catalyst layer. (c) 2008 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.