3-(Carboxymethyl)benzothiazolium bromide, a halogenated building block, is a thiazole derivative. 3-(Carboxymethyl)benzothiazolium bromide (3-(carboxymethyl)-2-methylbenzothiazolium bromide) is a benzothiazolium salt. Synthesis of 3-(carboxymethyl)benzothiazolium bromide has been reported. It can be prepared by reacting 2-methylbenzothiazole with bromoacetic acid.