Over the past few decades, considerable body of work has been carried out on the poly(4-bromostyrene) (PBrS) statistical copolymer poly(styrene-co-4-bromostyrene) (PBr_xS), where x denotes the mole fraction of 4-bromostyrene (4-BrS), because of their excellent flame retarding properties, strong affinity to silica substrate, and the immiscible character with polystyrene. A variety of synthetic methods for obtaining PBrS and PBr_xS have been described and utilized, including, radical, cationic, anionic, and living radical polymerization, and bromination of polystyrene. Bromination of polystyrene (PS) in good solvents, such as nitrobenzene or chloroform, has been used quite frequently for preparing PBr_xS with random sequences of stryrene and 4-BrS units. We have recently shown that by a slight modification of the bromination condition, this methodology can be used to tailor the “degree of blockiness” in PBr_xS. Specifically, by decreasing the solvent quality in bromination of parent PS from good to theta to poor, the co-monomer sequences distribution of styrene and 4-BrS changes from random (r-PBr_xS) to random-blocky (b-PBr_xS). Here we report on a systematic study examining the effect of solvent quality on the rate of bromination. The rate of bromination in nitrobenzene (NB, good solvent for PS), chlorodecane (CD, good solvent for PS), chloroundecane (CUD, theta solvent for PS), and chlorododecane (CDD, poor solvent for PS) is monitored by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and elemental analysis (EA). Our results indicate that under good solvent conditions the activation energy for bromination (E_A) scales inversely with the dielectric constant of the solvent (E_A,NB≈7 kJ/mol and E_A,CD≈45 kJ/mol). Our results also show that while CDD has a slightly higher dielectric constant than CD, it has E_A,CDD≈51 kJ/mol (higher than E_A,CD) because of the poor solvent conditions. Regardless of the solvent quality, the bulk bromination seems to follow the second order reaction kinetics. In addition, we show that one can elucidate rates of bromination of PS grafted chemically to flat substrates by performing the bromination reaction in a gradient set up on a single sample. Due to the steric hindrance of bromine molecules, the rate of bromination in surface-grafted PS is much slower relative to that in bulk. We thus conclude that the overall rate of bromination depends on not only chemical reaction rate but also physical accessibility of the reactant.