Gold Y-type zeolite catalysts were prepared by adding Y-type zeolite to a stirred aqueous solution of chloroauric acid. It was demonstrated that the ion-exchange process between gold ions and the zeolite dominated the preparation of gold into Y-type zeolite. The exchanged gold/Y catalysts possessed high catalytic activities for low-temperature carbon monoxide oxidation without any pretreatment. The activity could be promoted by addition of sodium hydroxide to the preparation solution. promotion was attributed to the substitution of OH- for the chloride around the gold ions. During the activity test, these gold catalysts were deactivated as a result of the transformation of active gold(III) species into gold metal of poor activity.