Abstract: A process for the preparation of a hydrocarbon resin which comprises polymerizing a mixture of (a) from 30 to 90% by weight of a dicyclopentadiene component comprising dicyclopentadiene and up to 30% by weight of an at most dialkylated dicyclopentadiene having from 1 to 4 carbon atoms in each alkyl substituent and (b) from 10 to 70% by weight of an aliphatic olefin containing 8 carbon atoms in the presence of a Friedel-Crafts catalyst and a solvent at a temperature of from 30.degree. to 140.degree. C wherein the polymer obtained is isolated as such or subsequently hydrogenated, and hydrocarbon resins prepared according to said process.