The combined use of contrast staining agents and X-ray microfocus computed tomography (microCT), referred to as contrast-enhanced X-ray microCT (CE-CT), can provide a solution for ex vivo 3D multi-tissue imaging of biological tissues. While many reported contrast agents (CAs) are destructive for the samples or toxic, we screened and validated different Wells-Dawson polyoxometalate formulations for visualization of biological tissues using CE-CT.