A novel hyperbranched poly(thienylene-phenylene) is synthesized, which is compared with a poly(2,3-thienylene-phenylene) and a poly(2,5-thienylene-phenylene). The hyperbranched polymer has much greater solubility in organic solvents than its isomeric linear polymers. A pronounced ionochromic effect is observed for the poly(2,5-thienylene-phenylene) in the presence of LiBF4. This polymer shows a large red shift in its UV-vis spectrum when treated with the metal salt solution. The ionochromic effect is also ion selective. However, both the hyperbranched polymer and the poly(2,3-thienylene-phenylene) show almost no such ionochromic effect probably because of the ortho-substituted thiophene units in their structure. The hyperbranched polymer and the poly(2,5-thienylene-phenylene) are found to be green light emitters and the poly(2,3-thienylene-phenylene) a blue light emitter. These materials are potentially useful for electroluminescence and photovoltaics.