The present invention relates to an organic filler, wherein a covalent bonding of at least one organic modifier to the organic filler has been effected at least via a part of the oxygen atoms of at least one functional group of the filler which is selected from phenolic OH groups, phenolate groups, aliphatic OH groups, carboxylic acid groups, carboxylate groups and mixtures thereof, a rubber composition comprising at least one rubber and at least the filler mentioned hereinabove, a vulcanizable rubber composition that additionally comprises a vulcanization system, a vulcanized rubber composition obtainable therefrom, as well as a use of the filler mentioned hereinabove for the production of (vulcanizable) rubber compositions for employment in the production of tires, preferably pneumatic tires and solid tires, preferably for the tread, sidewall and/or inner liner thereof, respectively, and/or for employment in the production of technical rubber articles, preferably profiles, seals, dampers and/or hoses.