The influence of the agglomeration with a clay binder on the activity of two 3D zeolites with medium and large pore size (ZSM-5 and beta) for the hydroisomerization of n-butane has been studied. Temperature-programmed desorption of ammonia (TPDA), atomic absorption (AA) spectroscopy, chemisorption and surface area measurements were used to characterize the catalysts. Catalytic performance is strongly influenced by the binder due to the fact that zeolite hydrogen transfer activity, metal/acid site balance, acid site density, and diffusional limitations are altered after agglomeration. A lower conversion is always obtained for the binded catalysts, due to neutralization of some zeolite acid centers. For the catalysts based on ZSM-5, it is compensated by a higher selectivity to iso-butane, but this positive effect is not observed for the catalysts based on beta zeolite.