Novel sulfonated poly(aryl ether ketones) containing benzoxazole were directly synthesized by aromatic nucleophilic polycondensation using various ratios of 2,2'-bi[2-(4-flurophenyl)benzoxazol-6-yl]hexafluoropropane to sodium 5,5'-carbonylbis(2-fluorobenzenesulfonate). The copolymers were soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide at a relatively high solid composition (>15 wt%) and formed tough, flexible and transparent membranes. The membranes exhibited a degradation temperature of above 290 °C. The exact dissolution times of these membranes at 80 °C in Fenton’s reagent (3 wt% H2O2 containing 2 ppm FeSO4) were undetectable, confirming their excellent chemical stability in fuel cell application. The membranes showed a moderate increase in water uptake with respect to increasing temperature. The proton conductivities of the membranes were dependent on the composition and ranged from 1.10× 10-2 to 5.50×10-2 Scm-1 at 80 °C and 95% relative humidity (RH). At 120 °C without externally humidified conditions, the conductivities increased above 10-2 Scm-1 with respect to increasing benzoxazole content, which suggested that the benzoxazole moieties contributed to the proton conduction.