The paper focuses on the chem. mechanisms involved during the prepn. of gold catalysts supported on alumina and titania and on attempts to simplify the procedures of prepn. Three methods involving the same gold loading (1 wt%) and the same precursor, HAuCl4, were studied: impregnation in excess of soln., anion adsorption and deposition-pptn. with urea. Regarding the first point, we showed that 1 wt% Au corresponds to a gold loading lower than the capacity of adsorption of the supports and that the three methods consist of a first common step of adsorption of anionic hydroxychloro gold complexes. The chem. mechanism involved during deposition-pptn. with urea was compared to that previously proposed for higher gold loading (8 wt%), and it was found that the time of contact between the support and the soln. could be drastically shortened (from 16 to 1 h). Regarding other simplifications of the prepns., the necessity of the washing step to eliminate the chlorine was investigated. In contrast to calcination, thermal treatment in hydrogen of samples still contg. chlorine leads to rather small gold particles (<5 nm), but not to chlorine elimination. As in the case of CO oxidn., the presence of chlorine was found detrimental for selective hydrogenation of butadiene. However, chlorine can be eliminated from the samples prepd. by impregnation or anion adsorption by washing with ammonia soln. of low concn. In the case of the deposition-pptn. with urea, water washing is sufficient to eliminate the remaining chlorine. [on SciFinder(R)]