A process is disclosed for preparing microcapsules having a shell thickness of at least 18 nanometers by polymerizing a tetraalkoxysilane at the oil/water interface of an emulsion containing 0.1 to 0.3 weight percent of a cationic surfactant. The microcapsules are useful to prepare encapsulated sunscreens having sufficient robustness to prevent leakage of the encapsulated sunscreen in a formulated composition.