The invention relates to a method for producing leather, characterized in that following liming, deliming and, optionally, souring, animal skins are pre-tanned or tanned with a mixture of compounds, comprising: (a) at least one organic tanning agent and; (b) a mixture consisting of: (b1) at least one C3-C12 dicarboxylic acid, and; (b2) of at least one other acid compound selected among C1-C3 mono- or C3-C12 dicarboxylic acids or salts thereof.