A zirconium cross-linking agent produced by a process which comprises contacting a zirconium triethanolamine complex with a mixture of polyols, which mixture comprises a hydroxyalkylated diamine and a hydrocarbon polyol. There is further provided a cross-linking composition which comprises (a) an aqueous liquid, (b) a cross-linkable organic polymer, and (c) a solution of a zirconium cross-linking agent which is produced by a process which comprises contacting a zirconium triethanolamine complex having a molar ratio of 1:2 to 1:5 of zirconium to triethanolamine with a mixture of polyols, which mixture comprises a hydroxyalkylated diamine and a hydrocarbon polyol wherein the molar ratio of zirconium to hydroxyalkylated diamine is 1:0.5 to 1:1 and the molar ratio of zirconium to hydrocarbon polyol is 1:0.5 to 1:1.5. The composition can be used in oil field applications for hydraulic fracturing and plugging of permeable zones and leaks in subterranean formations.