Water-in-oil (w/o) microemulsions are favorable for loading metal particles with a narrow size distribution. In the present paper, Pt-loaded beta-type zeolite catalysts were prepared by immobilizing Pt complex particles, which were synthesized using w/o microemulsions, onto a zeolite support. Loaded Pt particles were within the size range of 4.8-5.9 nm regardless of Pt content, whereas the Pt particle size of Pt-loaded catalysts prepared by the impregnation method increased from 1.7 to 13.1 nm with increasing Pt content. The Pt particle density was estimated based on the characterization data assuming that the Pt particles were equally loaded onto the mesopores. The Pt particle density of the Pt-loaded zeolite catalysts prepared using w/o microemulsions was dependent on the Pt content at a nearly constant Pt particle size. The effect of the Pt particle density on hydrocracking performance, such as jet fuel yield, was investigated using an autoclave at an initial H-2 pressure of 3 MPa and 300 degrees C in hydrocracking of the Fischer-Tropsch (FT) products over the Pt-loaded catalysts. When a constant amount of Pt was used, the maximum yield of corresponding jet fuel with carbon numbers of 9-15 (31.9%) was obtained at a Pt particle density of 0.9 x 10(12) m(-2). At a constant catalyst weight, the corresponding jet fuel yield was maximized (27.8%) at a Pt particle density of 0.9 x 10(12)-1.1 x 10(12) m(-2). (C) 2015 Elsevier B.V. All rights reserved.