Diatomite wet foams were stabilized by diatomite particles that were rendered partially hydrophobic by hexylamine, dried, and then sintered. The particle-stabilized diatomite foam contained primary pores with a size of 50 to 200 µm, formed by particles irreversibly adsorbed at liquid–gas interfaces, and secondary pores with a size of about 3 µm, induced by both its irregular particle shapes and inherent pores. In this study, we described a method of preparing diatomite foam with a bimodal pore structure and investigated pore characteristics of the diatomite foam by scanning electron micrographs, mercury porosimetry, and capillary flow porosimetry.