Experiments of pyrolysis of commercial Kraft lignin have been realized in the 250-550 °C range. Product analyses have been performed by FTIR, GC-MS, EDX analyses. The main goal of the work is to optimize the experiments in terms of liquid yield, reduction of oxygen content in the resulting biochar, and removal of sulfur, found mainly in the gas phase. It has been concluded that the amount of the starting lignin charged in the reactor must be limited to be fully positioned in the heating chamber also during high temperature treatment. Sulfur may be partially removed in the gas phase as H2S and CH3SH mainly, by a pre-treatment at 250 °C. The maximum amount of liquid product, mainly constituted by methoxy- and alkyl-methoxy-phenols, and the maximum solid deoxygenation are both obtained at 550 °C.