A colouring composition, preferably an ink for ink jet printing, comprising: 3.0 - 15.0% by weight, preferably 8.0-15.0% by weight, more preferably 7.0-12.5% by weight, of Ti in the form of a titanium compound obtained by a process comprising: (i) reacting at least one titanium alkoxide of formula Ti 4, wherein R1 is a linear or branched C1-C4 saturated alkyl radical, with water and, optionally, at least one alcohol, obtaining a first reaction mixture; (ii) adding glycolic acid to the reaction mixture of step (i) in a Ti:acid molar ratio comprised between 1:0.8 and 1:2.0, obtaining a second reaction mixture comprising water, alcohol and at least one intermediate titanium compound; (iii) optionally, but preferably, at least partially removing the water and alcohol from the second reaction mixture; (iv) adding to the mixture of step (ii) or of step (iii) at least one compound of formula N 3, wherein the R2 groups, whether the same or different from each other, are independently selected from the group consisting of H, - CO(NH 2), linear or branched C1-C4 alkyl radicals, linear or branched C1-C4 alcohols, and combinations thereof, in a Ti:N 3 molar ratio comprised between 1:0.20 and 1:1.50; and (v) completely eliminating the alcohol from the mixture of step (iv); 0.2 - 2.5% by weight, preferably 0.8 - 1.5% by weight, of Cr and/or Ni in the form of a water-soluble organic compound of Cr and/or a water-soluble organic compound of Ni; up to 100% by weight of a solvent selected from the group consisting of water, organic solvents miscible with water and mixtures thereof, wherein the quantities, and refer to the overall weight of the colouring composition. 3.0 - 15.0% by weight, preferably 8.0-15.0% by weight, more preferably 7.0-12.5% by weight, of Ti in the form of a titanium compound obtained by a process comprising: (i) reacting at least one titanium alkoxide of formula Ti 4, wherein R1 is a linear or branched C1-C4 saturated alkyl radical, with water and, optionally, at least one alcohol, obtaining a first reaction mixture; (ii) adding glycolic acid to the reaction mixture of step (i) in a Ti:acid molar ratio comprised between 1:0.8 and 1:2.0, obtaining a second reaction mixture comprising water, alcohol and at least one intermediate titanium compound; (iii) optionally, but preferably, at least partially removing the water and alcohol from the second reaction mixture; (iv) adding to the mixture of step (ii) or of step (iii) at least one compound of formula N 3, wherein the R2 groups, whether the same or different from each other, are independently selected from the group consisting of H, - CO(NH 2), linear or branched C1-C4 alkyl radicals, linear or branched C1-C4 alcohols, and combinations thereof, in a Ti:N 3 molar ratio comprised between 1:0.20 and 1:1.50; and (v) completely eliminating the alcohol from the mixture of step (iv); (i) reacting at least one titanium alkoxide of formula Ti 4, wherein R1 is a linear or branched C1-C4 saturated alkyl radical, with water and, optionally, at least one alcohol, obtaining a first reaction mixture; (ii) adding glycolic acid to the reaction mixture of step (i) in a Ti:acid molar ratio comprised between 1:0.8 and 1:2.0, obtaining a second reaction mixture comprising water, alcohol and at least one intermediate titanium compound; (iii) optionally, but preferably, at least partially removing the water and alcohol from the second reaction mixture; (iv) adding to the mixture of step (ii) or of step (iii) at least one compound of formula N 3, wherein the R2 groups, whether the same or different from each other, are independently selected from the group consisting of H, - CO(NH 2), linear or branched C1-C4 alkyl radicals, linear or branched C1-C4 alcohols, and combinations thereof, in a Ti:N 3 molar ratio comprised between 1:0.20 and 1:1.50; and (v) completely eliminating the alcohol from the mixture of step (iv); 0.2 - 2.5% by weight, preferably 0.8 - 1.5% by weight, of Cr and/or Ni in the form of a water-soluble organic compound of Cr and/or a water-soluble organic compound of Ni; up to 100% by weight of a solvent selected from the group consisting of water, organic solvents miscible with water and mixtures thereof, wherein the quantities, and refer to the overall weight of the colouring composition.