The pH value of microemulsion and HSM was 5.2–5.9 and 6.4–6.9 respectively. ThepH near to 7 indicates HSM could result less stimulation to skinthan ME. The average droplet size of ME and its gels was rangedfrom 38 .6 to 82.6 nm and 42.3 to 91.7 nm respectively. It indicatedthat the gel network of Carbopol 940 could not markedly influencethe diameter of ME droplets.