2,6-Dibromo-4,8-bis(octyloxy)benzo[1,2-b:4,5-b']dithiophene (CAS# 1294515-75-5) is a building block used in the preparation of low-bandgap conjugated polymers for solar cell applications, and in the synthesis of bi-diketopyrrolopyrrole as an electron-accepting copolymer.