A novel diamine monomer was prepared in three steps: first, a nucleophilic substitution reaction between hydroquinone and 1‐flouro‐4‐nitrobenzene afforded a nitro compound. Second, the nitro group of this compound was converted to an amino group via reduction in the presence of hydrazine hydrate. In the last step, the reaction of this compound with 4,4'‐diflouro benzophenone led to the synthesis of a novel ether keto diamine. Characterization of all materials was carried out by conventional spectroscopic methods and elemental analysis. A series of new polyureas was prepared via the polymerization reaction of the synthesized diamine with three commercially available diisocyanates including 4,4'‐diphenylmethan diisocyanate, toluene‐2,4‐diisocyanate, and isophoronediisocyanate in N‐methyl‐2‐pyrrolidone. The resulted polyureas were characterized by infrared spectroscopy and elemental analysis. The inherent viscosities of these polyureas ranged from 0.59 to 0.62 dL/g measured at a concentration of 0.5 g/dL. The resulting polyureas were soluble in dipolar aprotic solvents. The thermal properties of the polymers were investigated by differential scanning calorimetry and thermogravimetric analysis. The results indicated that their glass transition temperature values were between 171 and 198°C and at the 10% weight loss of polymers, glass transition temperature was about 325–368°C showing improved thermal stability in comparison with common polyureas. Thermal stability features of the polyurea were also confirmed by means of the pyrolysis‐gas chromatography/mass spectrometry method.