The pi-conjugated polymer poly(p-diethynylbenzene) (PDEB) has potential applications in electronics and optics; however, its poor solubility and processability have limited its usefulness. The new synthesis reported here makes use of a novel nickel catalyst, and gives rise to PDEB with good solubility and excellent thermal stability characteristics. The polymer exhibits fair photoluminescence and electroluminescence, a large third-order nonlinear optical susceptibility, and good humidity sensitivity, while doped PDEB shows semiconductor characteristics.