Abstract: The synthesis of copolyfluorenes by the Suzuki method under microwave heating carried out under conditions that were previously used for convection heating in an open system is studied. Using size-exclusion liquid chromatography, the stages of polycondensation, namely, oligomer formation, chain growth, and end group termination, are examined. The influence of temperature, solvent, and catalyst type Pd(PPh₃)₄, PdCl₂(dppf), polymer-bound Pd(PPh₃)₄, and SiliaCatDPP-Pd on the molecular-mass characteristics of the polymers is analyzed. The optical properties of new copolyfluorenes obtained by different methods are compared.