An experimental study was carried out to characterize the formation of 2-(2'-hydroxy-5'-methy1-pheny1)-2H-triazobenzene[tinuvin P] from the liquid phase reduction of 2-nitro-2'-hydroxy-5'-methyl azobenzene[methylazo dye] over Pd/C catalysts in the xylene-water-n-butylamine system. It was observed that this reaction was fully affected by the presence of water and n-butylamine. In older to investigate the effects of Pd/C states on the reaction, the effects of carbon preliminary treatment and palladium precursor were observed. According to the experimental results, reduced state of palladium was related to the formation of tinuvin P. The residual chloride on the catalyst prepared from palladium chloride deterred the reduction activity.