The effects of the mixing process and pH on the available chlorine content of the decontaminant calcium hypochlorite (or high-test hypochlorite, HTH) in the organic solvent-HTH-water mixture have been studied in order to develop new emulsion systems for the decontamination of polymer-thickened chemical warfare agents. A series of water-soluble and water-insoluble organic solvents were investigated. The observed temperature increase during the mixing of the water-soluble organic solvents with HTH and water was found to be mostly resulted from the mixing enthalpy of the solvent with water. It can be minimized by using a new mixing procedure. The effectiveness of HTH as the decontaminant was evaluated by monitoring the available chlorine content of the system at various time intervals after mixing. An increase in the basicity of the solvent-HTH-water system generally leads to a higher chlorine content. For the systems with the water-insoluble organic solvents, there was neither noticeable increase in temperature during the mixing nor significant loss of the chlorine content.