SPEEK-based composite membranes containing various amounts of titania nanosheets (TNS) as inorganic fillers were investigated for proton exchange membrane fuel cell applications. The samples were characterized for water uptake, proton conductivity (EIS), and structural features (SEM and XRD). Composites at low inorganic additive contents exhibited improved properties in terms of proton conductivity and water uptake behavior. Best improvements were observed for the composite containing only 0.95 wt% of TNS. This result could be associated to the unique nature of the two dimensional nanostructure of the inorganic additive.