A material which is suitable as filler or coating pigment for a fibrous web and a method for manufacturing thereof. According to the method, a feed comprising organic polymer material is cooled to at least approximately -50.degree. C., after which it is refined in a jet refiner to a desired particle size. The present invention generates uniform pigment particles which comprise, for instance, starch esters, and which particles have a porous surface structure, in which case they are suitable for instance as coating pigments and fillers for offset and ink-jet papers.