Organocell lignin has been subjected to catalytic hydrocracking in a semicontinuous reactor system using four petroleum-derived slurry oils and a lignin-derived one. The objective was to maximize the yield of phenols which can be further converted to methylarylethers for the use as gasoline octane number improvement. Experiments were carried out by varying temperature (375 degrees-450 degrees C), hydrogen pressure (75-180 bar), and catalyst (sulfided NiMo, zeolite A, and none). The most complete conversion (coke formation only 0.3%) was obtained at 375 degrees C and 180 bar when lignin was mixed with a lignin-derived slurry oil. The formation of phenols was monitored by quantitative capillary gas chromatography. Up to 12.8wt% (based on lignin) of a mixture of mono-phenols was obtained. The yields of single products (in wt% based on lignin) are as follows: phenol 2.3, cresols 5.0, xylenols 4.2, guaiacol 1.3.