Development of various transition-metal catalysts, including metathesis catalysts (W, Mo, Ta, and Nb) and Rh catalysts, has enabled the synthesis of a variety of substituted polyacetylenes, i.e. polymers from aromatic and aliphatic, and mono- and disubstituted acetylenes. The formed polymers possess carbon-carbon alternating double bonds along the main chain and various side groups. Therefore, they exhibit unique and interesting properties based on the conjugated structure, such as semiconductivity, photoluminescence, electroluminescence, electrochromism, and energy migration and transfer. This chapter deals with the polymerization of substituted acetylenes and characterization of the formed polymers with a focus on the experimental details of their synthesis.