The reaction of calcium oxide, P4S10, and water in the presence of calcium alkylarylsulfonate as a surfactant and tetrahydrofuran and xylene as solvents leads to a mixture of calcium mono-, di-, and trithiophosphate as colloidal particles stabilized by the surfactant in a hydrocarbon medium. A mechanism of the formation of the colloidal particles is proposed on the basis of systematic studies of the reaction medium and the characterization of the colloidal particles performed by means of chemical analyses, P-31 NMR and SAXS. The initial step is a reaction of a water-in-oil microemulsion with solid calcium oxide. The resulting reverse micelles containing water and solubilized calcium hydroxide further react with solid P4S10 to yield colloidal particles of calcium thiophosphates. The influences of the surfactant concentration, water, and THF contents have been investigated. THF acts as a cosurfactant and is absolutely required in order to obtain thiophosphates instead of phosphates.