Process for separating NH3 from a mixture containing NH3, CO2 and H2O which comprises an NH3 rectification step carried out in an NH3 separation device to which one or more streams containing NH3, CO2 and H2O, including the mixture, are fed from elsewhere in the process, with a stream consisting substantially of gaseous NH3 being formed in the NH3 separation device, separated from the mixture and discharged, wherein a condensation step is carried out in a condenser separate from the NH3 separation device on at least one of the stream consisting substantially of gaseous NH3 or the one or more streams containing NH3, CO2 and H2O supplied to the NH3 separation device, in which at least a part of the existing CO2 is converted to a liquid phase.