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The results of the development work on cementing hydrate-sludge pulp extracted from storage containers at the radiochemical plant of the Mining-Chemical Combine are presented. The work was performed on dummy wastes and real pulp under laboratory conditions as well as on an experimental cementing facility with a pulsation-type mixer developed at the Bochvar All-Russia Research Institute for Inorganic Materials. The properties determining the quality of the cement compound -mechanical strength under compression, water-and frost-resistance, leaching of 137 Cs -as well as important technological characteristics, such as cement spreadability and heat release during hydration of the binder were determined for different matrix mixes differing by composition, water/binder ratio, degree of pulp inclusion and form of the binder and sorption additive.Storage containers for hydroxide pulp from a radiochemical plant at the Mining-Chemical Combine are now being decommissioned because their nominal service life has been exhausted. Several thousand cubic meters of pulp with complex chemical composition -polyuranates and sodium aluminum hydroxycarbonates, polymerized plutonium hydroxide, and Fe, Cr, Mn, and Ni hydroxides, polymerized silicic acid, and nickel and cesium ferrocyanides -have accumulated in these containers. The solid-phase content comprises 100 ± 60 g/liter and the β-activity determined mainly by 90 Sr is the range 3.7·10 10 ± 1.85·10 10 Bq/kg. Under the conditions of long-term storage of pulp in these containers, 137 Cs and 239 Pu present the greatest radiation hazard.The decommissioning of the storage containers involves the following: 1) current operations -pulp extraction from the storage containers, processing with acid reagents to dissolve the solid phase, extractive separation of uranium and plutonium, collection and temporary storage of the insoluble pulp residues;2) planned operations -immobilization of insoluble residues in a solid water-resistant matrix composition (cement compound) for reliable localization (by the cement compound) of radionuclides and safe long-term storage of the cement compound.The present work is devoted to the development of a technology and equipment for immobilizing insoluble residues formed as a result of acid treatment of the initial pulp from the storage containers. Cementing was chosen because it has certain advantages over a different technology used to condition liquid radwastes:• the cement matrix retains uranium and plutonium by forming complex compounds;• the most mobile isotope 137 Cs can be fixed in the cement matrix by using sorption additives;