Propoxylated sorbitol was converted to a polyurethane-polyisocyanurate foam in reaction with diphenylmethane diisocyanurate in presence of triethylenediamine, 1,3,5-triethanolhexahydro-s-triazin or AcOK catalysts, a silicone foam stabilizer and distd. H2O at 155 degrees C for 12 min. The foams were studied for compressive strength absorption of H2O and structure. The best foam quality was achieved when 1,3,5-triethanolhexahydro-s-triazin were used.