HT-poly(3-hexylthiophenes) (HT-PHT) with H/Br end group composition were prepared via a modified McCullough method using anhydrous ZnCl2 for the transmetalation step. These bromine-terminated HT-PHT can be end group modified at the o) end through a cross-coupling reaction with thienylzinc compounds bearing a THP-protected hydroxy or STABASE-protected amino groups. After deprotection, HT-PHTs with -OH or -NH2 functional groups at the o) end were obtained. In addition, HT-PHT with pure H/H end group composition were also modified by treatment with Vilsmeier reagent and functionalized with formaldehyde groups at both the a and 0) chain ends. Reduction of the formaldehyde groups produced the HT-PHT diol. MALDI-TOF is a powerful tool to monitor each step of these end group functionalizations.