Abstract: A process for the large-scale production of therapeutic grade thrombin of excellent viral safety and storage-stability is carried out by purification of viricide treated crude thrombin by ion-exchange chromatography on a single column using a sulfalkyl-activated polysaccharide, particularly a non-compressible composite medium of sulfoalkyl-activated dextran and silica particles, as the ion exchange medium and using increasing concentrations of phosphate buffer for elution. After recovery of thrombin in the final eluate, the phosphate buffer is exchanged for a stabilizing formulation buffer, and the stabilized thrombin is subjected to viral filtration and optional dry heat treatment for further viral inactivation. The final product has high specific activity and is obtained in good yield.