We studied the influence of swelling agents on pore size distributions in the shell of porous silica-alumina hollow sphere particles for acid-promoted hydrolytic generation of hydrogen from ammonia borane. Their well-ordered porous shells were formed with micelle templates of cetyltrimethylammonium bromide on spherical polystyrene (PS) particle templates, and swelling agents were introduced into the micelle templates for expanding the pores. Non-polar agents (hexane and toluene) did not significantly influence the size of the pores, whereas, polar agents (1-dodecanol and 1-dodecylamine) effectively expanded the pores. The hollow sphere particles formed with 1-dodecylamine possessed narrow pore distribution with a high peak pore volume. The activity of the hollow sphere particles in the hydrolytic generation of hydrogen increased according to increasing pore size with a narrow distribution, and the hollow sphere particles formed with 1-dodecylamine showed an approximately five times higher TOF for the hydrogen evolution than those formed without a swelling agent. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.