Boron carbide has been proposed for the neutron protection of equipment in the ITER diagnostic ports and for reducing the dose to maintenance personnel. The chemical composition, vacuum, and thermal properties of ceramics of boron carbide were studied. It is demonstrated that the outgassing rate of ceramics meets the requirements of the ITER Vacuum Handbook. Calculation of the total gas emission from the ITER equatorial port #11 is carried out. The contact thermal conductivity at the boundary between ceramics and bronze is measured. Manganese content is determined by the method of activation analysis in ceramics. It is shown that sintered and hot-pressed boron carbide ceramics can be used in the ITER diagnostic ports.