Abstract: The thick CaO targets were investigated for the radioactive ³⁷K ion beam generation by the ⁴⁰Ca(p, α)³⁷K reaction. The CaO targets are the low-density, fibrous, highly permeable target materials. And they form the fast diffusion-release, mechanically and thermally stable production targets for the radioactive ³⁷K ion beam research applications. The low-density reticulated vitreous carbon fiber (RVCF) was used as the target matrix. The protective W layer with thickness of 1.2 μm was pre-coated onto the matrix by the chemical vapour deposition technology to prevent the undesired reaction process at a relatively high temperature. The CaO target material was deposited onto the W/RVCF matrix by the paint coating technology. The thickness of every part for the CaO/W/RVCF compound target was designed according to the calculation results of the energy loss and cross-section. The radiating structure of the target chamber was also designed and machined. The temperature distributions of the compound target and target chamber bombarded by different proton beam powers were simulated by the Comsol multiphysics code. The maximum proton beam power bombarding onto the CaO/W/RVCF compound porous target was found to be 7.5 kW for the present radiating structure of the target chamber.