Abstract: The present invention relates to a method for treating a mixture containing cellulose, comprising at least one step of adding at least one agent capable of reducing carbonyl groups. The invention further relates to a specialty cellulose pulp, obtained by a method comprising said treatment. Furthermore, the invention relates to the use of the specialty cellulose pulp according to the invention or the specialty cellulose pulp obtained by a method according to the invention for the production of cellulose derivatives or materials containing cellulose molecules, including but not limited to, cellulose ethers or cellulose esters. Cellulose derivatives obtained from the specialty cellulose pulp according to the invention display increased viscosity and/or improved brightness over cellulose derivatives obtained from specialty cellulose pulp not subjected to the inventive treatment.