(1) Hollow silica particles in which the shell part has a mesoporous structure having an average pore diameter of 1-10 nm and which has an average particle diameter of 0.05-10 µm, at least 80% of all the particles having a particle diameter which is within the range of (average particle diameter)±30%; (2) composite silica particles in which the shell part has a mesoporous structure having an average pore diameter of 1-10 nm and which has a BET specific surface area of 100 m<SUP>2</SUP>/g or larger and each has a hydrophobic organic compound or high-molecular organic compound enclosed therein; and a process for producing the hollow silica particles.
