A composition comprising 0.1-99.9% by weight dispersible inorganic or organic pigment particles; and 0.1-99.9% by weight dispersing agents that essentially consist of a combination of (i) a block copolymer, {X-[(A x -B y)} p -Y], wherein X represents the fragment of a polymerisation initiator capable of initiating polymerisation of ethylenically unsaturated monomers by atom transfer radical polymerisation (ATRP) in the presence of a catalyst capable of activating controlled radical polymerisation by ATRP; Y represents a radically transferable group, a polymerisable chain terminal group or a saturated polymer chain terminal group; A and B represent polymer blocks composed of repeating units of ethylenically unsaturated monomers selected from the group consisting of styrenes, acrylic and methacrylic acid-C 1 -C 24 alkyl esters, acrylic and methacrylic acid-hydroxy-C 2 -C 6 alkyl esters, acrylic and methacrylic acid-dihydroxy-C 3 -C 4 alkyl esters and acrylic and methacrylic acid esters having poly-C 2 -C 4 alkyleneglycol ester groups, wherein the ester groups may be substituted with C 1 -C 24 alkoxy groups; and wherein at least one of the polymer blocks A or B or the chain terminal group Y additionally contains repeating units of ethylenically unsaturated monomers substituted with basic residues which are represented by a compound of the formula CH 2 =C(-R 1)-C(=O)-R 2, wherein R 1 represents hydrogen or methyl; and R 2 represents a basic residue selected from the group consisting of amino-C 2 -C 4 alkoxy, C 1 -C 4 alkylamino-C 2 -C 4 alkoxy, di-C 1- C 4 alkylamino-C 2 -C 4 alkoxy, hydroxy-C 2 -C 4 alkylamino-C 2 -C 18 alkoxy and C 1 -C 4 alkyl-(hydroxy-C 2 -C 4 alkyl)-amino-C 2 -C 4 alkoxy; one of x and y represents zero, one or a numeral greater than one and the other one represents a numeral greater than one; p and q represent one; and (ii) a salt forming compound selected from the group consisting of mono- or polycyclic sulphonic, mono- or polycyclic carboxylic or phosphonic acids, aliphatic sulphonic, carboxylic or phosphonic acids substituted with mono- or polycyclic groups, C 1 -C 8 alkyl halides substituted with mono- or polycyclic groups and C 1 -C 4 alkyl esters of mono- or polycyclic sulphonic acids; provided that p-toluenesulphonic acid is excluded. (i) a block copolymer, {X-[(A x -B y)} p -Y], wherein X represents the fragment of a polymerisation initiator capable of initiating polymerisation of ethylenically unsaturated monomers by atom transfer radical polymerisation (ATRP) in the presence of a catalyst capable of activating controlled radical polymerisation by ATRP; Y represents a radically transferable group, a polymerisable chain terminal group or a saturated polymer chain terminal group; A and B represent polymer blocks composed of repeating units of ethylenically unsaturated monomers selected from the group consisting of styrenes, acrylic and methacrylic acid-C 1 -C 24 alkyl esters, acrylic and methacrylic acid-hydroxy-C 2 -C 6 alkyl esters, acrylic and methacrylic acid-dihydroxy-C 3 -C 4 alkyl esters and acrylic and methacrylic acid esters having poly-C 2 -C 4 alkyleneglycol ester groups, wherein the ester groups may be substituted with C 1 -C 24 alkoxy groups; and wherein at least one of the polymer blocks A or B or the chain terminal group Y additionally contains repeating units of ethylenically unsaturated monomers substituted with basic residues which are represented by a compound of the formula CH 2 =C(-R 1)-C(=O)-R 2, wherein R 1 represents hydrogen or methyl; and R 2 represents a basic residue selected from the group consisting of amino-C 2 -C 4 alkoxy, C 1 -C 4 alkylamino-C 2 -C 4 alkoxy, di-C 1- C 4 alkylamino-C 2 -C 4 alkoxy, hydroxy-C 2 -C 4 alkylamino-C 2 -C 18 alkoxy and C 1 -C 4 alkyl-(hydroxy-C 2 -C 4 alkyl)-amino-C 2 -C 4 alkoxy; one of x and y represents zero, one or a numeral greater than one and the other one represents a numeral greater than one; p and q represent one; and X represents the fragment of a polymerisation initiator capable of initiating polymerisation of ethylenically unsaturated monomers by atom transfer radical polymerisation (ATRP) in the presence of a catalyst capable of activating controlled radical polymerisation by ATRP; Y represents a radically transferable group, a polymerisable chain terminal group or a saturated polymer chain terminal group; A and B represent polymer blocks composed of repeating units of ethylenically unsaturated monomers selected from the group consisting of styrenes, acrylic and methacrylic acid-C 1 -C 24 alkyl esters, acrylic and methacrylic acid-hydroxy-C 2 -C 6 alkyl esters, acrylic and methacrylic acid-dihydroxy-C 3 -C 4 alkyl esters and acrylic and methacrylic acid esters having poly-C 2 -C 4 alkyleneglycol ester groups, wherein the ester groups may be substituted with C 1 -C 24 alkoxy groups; R 1 represents hydrogen or methyl; and R 2 represents a basic residue selected from the group consisting of amino-C 2 -C 4 alkoxy, C 1 -C 4 alkylamino-C 2 -C 4 alkoxy, di-C 1- C 4 alkylamino-C 2 -C 4 alkoxy, hydroxy-C 2 -C 4 alkylamino-C 2 -C 18 alkoxy and C 1 -C 4 alkyl-(hydroxy-C 2 -C 4 alkyl)-amino-C 2 -C 4 alkoxy; (ii) a salt forming compound selected from the group consisting of mono- or polycyclic sulphonic, mono- or polycyclic carboxylic or phosphonic acids, aliphatic sulphonic, carboxylic or phosphonic acids substituted with mono- or polycyclic groups, C 1 -C 8 alkyl halides substituted with mono- or polycyclic groups and C 1 -C 4 alkyl esters of mono- or polycyclic sulphonic acids;