Siloxanes are prepared by reacting: a compound A with a compound B or a compound A with a compound C or a compound B with a compound C or a compound C alone, in the presence of a compound D at ≥40° C., wherein compound A is a silane or a siloxane having at least one silicon-bonded hydrogen atom, compound B is a silane or a siloxane having at least one silicon-bonded alkoxy moiety, compound C is a silane or a siloxane having at least one silicon-bonded hydrogen atom and at least one silicon-bonded alkoxy moiety, and compound D is a cationic Si(II) compound.