Alkyl-substituted poly(aryl ether ketone)s (PEKs), having more than two alkyl substituents per repeat unit, were synthesized by nucleophilic substitution reaction of 1,1’-(p-phenylene-dioxy)bis[2-methyl-4-(fluorobenzoyl)benzene] with an aromatic diol of different structure in the presence of a base. The resulting polymer showed high solubility toward polar organic solvents such as chloroform, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. The alkyl-substituted PEKs showed glass transition points of around 150 degrees C and were thermally stable up to 440 degrees C under nitrogen. Crystallinity of the polymer was examined by using WAXD.