Abstract: The transition metal modified series MOx-PdO/γ-Al₂O₃(M=La，Mn，Ni，Ce) catalysts were prepared by incipient wetness impregnation process，and their performances were evaluated in the direct synthesis of hydrogen peroxide from hydrogen and oxygen at 10 ℃ and atmospheric pressure.The effects of kinds of transition metal and loading amounts of La₂O₃ on the activity of MOx-PdO/γ-Al₂O₃ catalysts were investigated.The catalysts were characterized by means of energy dispersive spectrometer（EDS），X-ray diffraction（XRD），and temperature programmed reduction（H2-TPR） etc..Results showed that transition metal modified MOx-PdO/γ-Al₂O₃  catalyst′s performance was better than that of unmodified PdO/ γ-Al₂O₃.For all the catalysts investigated herein，the La₂O₃-PdO/γ-Al₂O₃ （mass fraction of La₂O₃ was 1% and mass fraction of PdO was 2.5%）catalyst showed significantly superior catalytic activity，and as compared to the original catalyst PdO/ γ-Al₂O₃，the concentration，yield and selectivity of hydrogen peroxide increased by 76.54%，76.61% and 44.21%，respec- tively.

Key words: Pd catalyst, transition metal, hydrogen peroxide, direct synthesis