As a new kind of drug carrier, practical applications of hollow periodic mesoporous organosilica (HPMO) have been greatly limited by their low loading capacity for hydrophobic drugs. In this work, we demon-strated the preparation of HPMO capsules with tunable shell thickness by using 1,2-bis(triethoxysilyl) ethane as the precursor. The capsules with thin shells and thus low Young''s modulus showed excellent swellability to organic solvents containing hydrophobic drugs. As a result, hydrophobic drugs, i.e., pacli-taxel (PTX) could be loaded into the hollow interior of the HPMO capsules with 4 nm shell at an efficiency of ca. 120 %. The as-prepared PTX-loaded HPMO capsules were dispersible in aqueous media and showed improved performance in killing cancer cells compared to free PTX.(c) 2022 Elsevier Inc. All rights reserved.