Random bulk polycondensation and the slow monomer addition (SMA) strategy have been employed for the preparation of hyperbranched aromatic homo- and copolyesters, based on 3,5-bis(trimethylsiloxy)benzoyl chloride (AB(2) monomer) and 3-(trimethylsiloxy)benzoyl chloride (AB comonomer). Whereas random copolycondensation in bulk yielded limited molecular weights (M-n = 2900-8400; SEC-LALLS in DMF/GHC), considerably higher molecular weights and low polydispersities were obtained under slow monomer addition conditions (M-n = 83 000-278 000; PD = 1.09-1.49). Copolymerization of the AB(2) and AB monomers resulted in polymers with controlled degrees of branching (DB) in the range 0-0.5. In the random copolycondensation the theoretical DB values could be confirmed by detailed analysis of the C-13 NMR data, demonstrating equal reactivity of the comonomers. Using the slow monomer addition strategy (SMA), the DB was significantly enhanced above the value of 0.5 for bulk AB(2) polycondensation to 0.61-0.66, in agreement with theoretical predictions (DB = 0.66), and also high molecular weight polymers were obtained. Also, for all copolymerizations enhanced DBs were obtained. A strictly linear dependence of the intrinsic viscosity [eta] on molecular weight was observed for all copolymers, measured by online SEC viscosimetry. The Mark-Houwink exponents alpha (MH) clearly decreased with the DB and were in the range 0.18-0.55.