Abstract: The present invention relates to the obtention of a rigid polyurethane compound, cellular or micro-cellular, reinforced or not, having a density ranging from 0.20 to 1.30 g/cm.sup.3 ; the formation of this compound happens through the mixing of a resin composed of a mixture of polyether and polyester polyols aminated or not, having a molecular weight ranging from 100 to 5000, employed at 5 to 100 parts by weight; surfactant based on dimethylpolysiloxane, employed at 0.1 to 5 parts by weight; amine catalysts of the tetramethylethylenediamine and dimethylcyclohexylamine type employed at 0.