Dicyanoacetylene has been homopolymerized and copolymerized with styrene by a free-radical initiator. The homopolymerization was difficult to effect, but the copolymerization proceeded very well, to essentially a quantitative yield. Proof of the existence of a true copolymer was obtained by means of solubility tests and infrared spectroscopy. In addition, the reactivity ratios were calculated by means of infrared spectroscopy and it was found that ther1andr2values for styrene and dicyanoacetylene were 1.40 and approximately zero, respectively.