This study presents a novel technique for the controllable preparation of calcium benzene sulfonate [Ca(Ar-SO3)(2)] detergents using a microdispersion process. Neutralization and carbonation were conducted in an oil-in-water system instead of the typical water-in-oil system. n-Butanol was employed as the oil phase for the in situ formation of the hydrophobic cores of the detergents. The mechanism of synthesis in different bulk phases was investigated. Microreactors were used to enhance the mixing performance and mass transfer. Low-cost Ca(OH)(2) and dodecyl benzene sulfonic acid (Ar-SO3H) were supplied as the reactants. An efficient synthesis with a high utilization ratio of CO2 and a high product yield was achieved. CaCO3 nanoparticles with average sizes from 8 to 20 nm were used as detergent cores, and Ca(Ar-SO3)(2) detergents with total base numbers (TBNs) ranging from 300 to 420 mg of KOH/g were successfully prepared.