A mixture of triphenylphosphine and zeolite Y was thermally treated in an autoclave (423 K, 24 h), resulting in the inclusion of PPh3 in the supercage of zeolite Y, up to 21 wt % (1.5 PPh3 molecules per supercage). PdCl2 was introduced to the PPh3-treated zeolite Y to fabricate a Pd complex in the supercage, and a coupling reaction was performed over the obtained complex. The turnover frequency increased with increased PPh3 loading, suggesting that the [PdCl2(PPh3)(2)] complex included in the supercage could be the active species.