Abstract: A green light-emitting fluorescent material prepared from terbium-activated lanthanum cerium orthophosphate expressed by the structural formula:La.sub.x Tb.sub.y Ce.sub.z PO.sub.4where:x+y+z=10.05<x<0.350.05<y<0.30.6<z<0.9and a fluorescent lamp comprising said green light-emitting fluorescent material used alone or in combination with any other form of fluorescent material.