By the methods of differential thermal analysis and X-ray phase analysis, we have investigated the interaction of an alloy based on SmCO5 with additives of the SmCO3 phase under initial hydrogen pressures of 0.3, 0.4, 0.5, and 0.6 DeD D degrees at temperatures of 713 and 913 K with holding for 2 and 5 h. At 713 K, only the compound SmCO3 interacts with hydrogen with the formation of unidentified phases. In holding at 913 K under a pressure of 0.3 and 0.4 DeD D degrees for tau = 2 and 5 h, the alloy partially disproportionates into samarium hydride and cobalt. It has been established that the complete disproportionation occurs in holding at pressures of 0.5 and 0.6 DeD D degrees and for tau = 2 and 5 h. In vacuum, at 1223 K, disproportionation products recombine in the initial phases.