Abstract: When producing green liquor for later manufacture of cooking liquor, it is endeavoured that the green liquor shall be readily clarified and/or readily filtered. This endeavour is achieved with the present invention, which relates to a method of producing green liquor in which waste liquor separated from cellulose pulp and derived from a cooking stage and possibly from one or more bleaching stages is worked up including known treatment stages such as evaporation, combustion, smelt dissolving and other green liquor preparation, and in which a calcium containing chemical is added to the waste liquor prior to combustion, or is added at the combustion of the waste liquor. The method is characterized in that carbon deriving from the smelt is caused to equal at most 0.