SYNTHESIS AND THERMAL BEHAVIOUR OF SOME BISMALEIMIDES WITH HEXAFLUOROISOPROPYLIDENE GROUPS Bismaleimide monomers were used to prepare polymers in an attempt to achieve good properties. Bismaleimide BMI (1-3) were synthesized by reaction of maleic anhydride with diamines having hexafluoroisopropylidene units. Bismaleimides BMI (4-5) with ester units were synthesized by reaction between 3(4)-maleimidobenzoylchloride with diphenols.The monomers were characterized by infrared (IR), proton nuclear resonance ( 1H-NMR ) spectroscopy and elemental analysis. Thermal characterization of monomers was accomplished by differential scanning calorimetry (DSC), dynamic thermogravimetric analysis (ATG) and isothermal gravimetric analysis (IGA). In this paper , the synthesis and characterization of monomers with fluoro atoms in their structure is discussed.