For an Abelian group G, any homomorphism µ : G ⊗ G → G is called a multiplication on G. The set Mult G of all multiplications on an Abelian group G itself is an Abelian group with respect to addition; the group is called the multiplication group of G. Let A 0 be the class of all reduced block-rigid almost completely decomposable groups of ring type with cyclic regulator quotient. In this paper, for groups G ∈ A 0 , we describe groups Mult G. We prove that for G ∈ A 0 , the group Mult G also belongs to the class A 0 . For any group G ∈ A 0 , we describe the rank, the regulator, the regulator index, invariants of near-isomorphism, a main decomposition, and a standard representation of the group Mult G.