A process for preparing a stable zirconium triethanolamine cross-linking agent comprises contacting a solution of a zirconium triethanolamine complex with water at a temperature of 50.degree. C. to 90.degree. C. at a mole ratio of triethanolamine:zirconium in the range of 3.5:5.5 and at a mole ratio of water:zirconium in the range of 20:1 to 1:1. The stable zirconium triethanolamine complex can be used in a cross-linking composition. Further disclosed are methods to use the composition in oil field applications for hydraulic fracturing and plugging of permeable zones and leaks in subterranean formations.