A series of PPV copolymers containing 2-nitro-1,4-phenylenevinylene (NO2-PV) units were prepared via the water-soluble precursor route. They were obtained in film form and were doped with I2 and FeCl3. Doping increased the electrical conductivities to maximum values of about 3 X 10(-2) and 3 X 10(-1) s cm-1, respectively, for the two dopants. Conductivity depended strongly on the composition of the copolymers; it reached a maximum value at ca. 1-2 mol % of NO2-PV units in the copolymers and then dropped rapidly with further increase in NO2-PV content. Electronic effects of the substituent and morphological changes induced by copolymerization appear to interplay intricately, resulting in the occurrence of a maximum conducting composition.