Several substituted benzyltrimethylammonium tribromides (BTMA Br_3) and phenyltrimethylammonium tribromide (PTMA Br_3) were prepared to compare their brominating ability with the mother compounds BTMA Br_3 and PTMA Br_3. Consequently, it turned out that electron donating substituent such as p-methyl group increased the brominating ability of the tribromides and electron attracting substituent such as p-nitro group decreased its ability of the tribromides.