Chitosan is an abundant naturally occurring biopolymer that is biocompatible, of low toxicity and is well suited as a carrier for a range of active agents. Restrictions imposed by this biopolymers unique solubility requirements make if difficult to process. One approach to an internal setting system is to employ the water-soluble blocked isocyanate hexamethylene-1,6-di(aminocarboxysulphonate) (HDACS) in order to cross-link the chitosan and form microspheres in situ utilizing simple emulsion systems. Chitothane microspheres are capable of delivering active agents at controlled release rates and offers a viable alternative to external set methodologies utilizing aldehydes or similar cross-linking agents.