Abstract: A polyurethane foam and associated production process, in particular flexible to semi-hard block foams or soft molded foams, using polyesters or polyethers as polyols. A carbamate, or a mixture of carbamates, is used simultaneously as propellant and as catalyst, wherein the carbamate or the carbamates have the general Formula I wherein: R1 and R2 represent the same or different alkyl radicals, R3 and R4 represent the same or different radicals and denote hydrogen or alkyl radicals, R5 denotes hydrogen, an alkanol radical, a polyether monool radical or the alkyl radical, characterized by X and n represents 2 or 3.