The invention is directed to a bitumen composition, to a paving, to a roofing, to a method for preparing a bitumen composition, to a method for increasing the stiffness of a bitumen composition, to a method of adjusting the physical properties of a bitumen composition, and to the use of a bitumen composition. The bitumen composition of the invention comprises a lignin compound or derivative thereof, wherein 10 wt. % or more by weight of said lignin compound or derivative thereof is molecularly dissolved in said bitumen composition.