Bis-ortho-diynylarene (BODA) monomers, prepared from common bisphenols in three high yielding steps, undergo free-radical-mediated thermal polymerization via an initial Bergman cyclo-rearrangement. Polymerization is carried out at 210 °C in solution or neat with large pre-vitrification melt windows (4–5 h) to form branched oligomers containing reactive pendant and terminal aryldiynes. Melt- and solution-processable oligomers with weight-average molecular weight Mw = 3000–24 000 g mol–1 can be coated as a thin film or molded using soft lithography techniques. Subsequent curing to 450 °C affords network polymers with no detectable glass transition temperatures below 400 °C and thermal stability ranging from 0.5–1.5 % h–1 isothermal weight loss measured at 450 °C under nitrogen. Heating to 900–1000 °C gives semiconductive glassy carbon in high yield. BODA monomer synthesis, network characterization and kinetics, processability, thin-film photoluminescence, and thermal properties are described.