A process for the preparation of dialkyl carbonates is described in which an alkylene carbonate is first formed from alkylene oxides and CO.sub.2 and this alkylene carbonate is then transesterified with alkanols. Both reaction steps are carried out in the presence of a bifunctional catalyst of the formula[A.sub.a -X.sub.b ].sub.m .multidot.[B.sub.c Y.sub.d ].sub.n (I)wherein A, B, X, Y and the indices a, b, c, d, m and n have the meaning indicated in the description.