The present study describe the preparation and characterisation of anhydrous proton conducting composite membranes based on sulfonated poly(ether ether ketone) [SPEEK-degree of sulfonation 70-72%]/ethyleneglycol [EG]/ionic liquid by solution casting method using water: ethanol (50:50) as solvent. For this purpose several composite membranes were prepared by mixing solution of SPEEK/ethylene glycol (67:33 wt %) in water: ethanol with varying amounts of 1-butyl-3-methyl-imidazolium trifluromethanesulfonate [bmim][OTf] ionic liquid. The cross-linking of SPEEK was carried out by thermal treatment i.e. by heating in vacuum oven at 80 degrees C (2 h), 100 degrees C (2 h), 120 degrees C (2 h) and 135 degrees C for 16 h. Ethylene glycol was used as a cross-linker for SPEEK to reduce the leaching out of ionic liquid and enhance the mechanical strength of SPEEK membranes. The membranes were characterized for thermal [thermogravimetry analysis], structural [FTIR-ATR], proton conductivity, morphology (XRD, SEM) and leaching out of ionic liquid with water. FTIR studies clearly showed the interactions between SPEEK, EG and ionic liquid. The proton conductivity and dynamic mechanical properties of the composite membranes were investigated at elevated temperature and under anhydrous conditions. Proton conductivity of all the membranes measured in the temperature range of 30-140 degrees C under anhydrous conditions was in the range of 10(-3) Scm(-1) which showed an increase with increase in temperature and amount of ionic liquid. (C) 2014 Elsevier Ltd. All rights reserved.