AbstractThe action of hydrogen bromide on non‐terminal glycol acids (threo and erythro‐6,7‐dihydroxystearic acids) leads to the formation of 6(7)–7(6)‐bromoacetoxystearic and 6(7)‐ketostearic acids as major and minor products of the reaction. On the other hand the same reaction on a terminal glycol acid, 10,11‐dihydroxyundecanoic yielded only one bromoacetoxy acid (10‐acetoxy‐11‐bromoundecanoic) and a diacetoxy derivative (10,11‐diacetoxyundecanoic) as minor and major products. Assignment of configuration and structures of reaction products are based on the I. R., N. M. R. and mass spectral studies. It is evident that hydrogen bromide reaction of the terminal glycol acid takes a different course from that observed in the nonter