Provided in the invention is an adhesion promoter (AP) that is the reaction product of: (i-1) at least one hydroxyl functional (meth)acrylated compound bearing at least two (meth)acryloyl groups, (i-2) optionally, at least one hydroxyl functional (meth)acrylated compound bearing one (meth)acryloyl group (ii), at least one titanium orthoester (ii-a) and/or at least one zirconium orthoester (ii-b), and, (iii) optionally, at least one other compound (iii) that is capable to react with hydroxyl groups. Materials of the invention are suitable for use in coating compositions, inks, paints, varnishes (including overprint varnishes), adhesives (including laminating adhesives), for the making of composites, molding compositions or 3D articles. Materials of the invention are suitable for use in inks and coating compositions (clear or pigmented).