A series of novel unsymmetrical diacetylenes have been prepared which have quinolyl moiety as one of the directly linked sidegroups to the acetylenic backbone. One of the diacetylenes exists in two crystal forms, one of which is solid state reactive. The polydiacetylenes obtained from the monomers have generally long effective conjugation length as indicated by their absorption spectra. The third-order nonlinear optical susceptibility (chi((3))) of one of the polydiacetylenes has been evaluated and found to be in the order of 10(-11) esu.