This paper describes test results for immobilization of surrogate radioactive actinide solutions. A glass crystalline porous material, Gubka, or “sponge” in Russian, was tested to immobilize surrogates of two types of actinide solutions, which exist in the DOE complex. Solutions using uranium as a surrogate for plutonium were stabilized in the porous Gubka block by successive saturation and drying cycles. After calcining, fully dense glass-ceramic tablets were formed in a hot uniaxial press. The tablets included 2–3 different glass phases with no uranium content and a uranium phase. Detailed electron micrographs and X-ray diffraction results are presented in the paper.