The synthesis of substituted poly(p-phenylenenvinylene) (PPV) was carried out via metathesis polycondensation of 2,5-diheptyl-1,4-divinylbenzene (DHepDVB). A stable molybdenum-carbene complex served as catalyst. The preparation of the educt employed (DHepDPV, 3 a) is described. The obtained poly(2,5-diheptyl-1,4-phenylenevinylene) (DHepPPV, 5), an intensely yellow product, has an all-trans-configuration and, with a degree of polymerization of approximate to 10 is soluble in conventional organic solvents.