The invention relates to a process for the preparation of branched siloxanes containing R—SiO3/2 units, where R=organic radical, wherein straight-chain polysiloxanes containing silane hydrogen in the polymer chain are reacted in the presence of ammonium or metal carboxylates as a catalyst in the absence of hydroxy-functional organic compounds, and to siloxanes thus prepared and the use thereof in the preparation of polyurethane foams and antifoam formulations.