A kit is provided based on two pastes designed to produce bone cement with high initial stability and therefore low post-cure. The kit includes a paste A and a paste B, wherein paste A contains (a1) a polymerizable monomer having a pH in water in the range of 5-9, (a2) a filling agent insoluble in (a1), and (a3) a barbituric acid derivative selected from the group consisting of 1,5-disubstituted barbiturates, 1,3,5-trisubstituted barbiturates, and 1,3,5-tetrasubstituted barbiturates, and paste B contains (b1) a polymerizable monomer having a pH in water in the range of 5-9, (b2) a filling agent insoluble in (b1), (b3) a peroxide soluble in (b1), (b4) a heavy metal compound insoluble in (b1) and selected from the group consisting of heavy metal salts and heavy metal complexes, and wherein at least one of the pastes A and B contains a halide salt.