The optical and electroluminescent properties of a novel soluble derivative of poly(p-phenylene vinylene), poly(2-methoxy-5butoxy-p-phenylene-vinylene)(MBPPV), and its polyblends were studied. We have fabricated a single-layer and double-layer structure of light-emitting devices (LEDs), with polyblends as the active layer. The turn-on voltage and maximum external quantum efficiency of the double-layered structure LEDs were 3.5 V and 1.35%.