AbstractThe reaction of methonol with ammonia over catalysts, used commercially today, to give methylamines, does not occur with the desired dimethylamine selectivity. Both a thermodynamically and kinetically controlled reaction over conventional catalysts permits a maximum dimethylamine selectivity (DMA selectivity) of only about 30 mol‐%. In addition to monomethylamine (MMA), a large amount of the undesirable trimethylamine (TMA) is formed. By using zeolites and taking advantage of their shap‐selective properties, it is possible to achieve high MMA and DMA selectivities. Shape‐selective catalysis can only take place at catalytically active centrs in the inteerior of the por system. The proportion of non‐shape‐selective catalysis at the active centres on the outer surfaces of zeolites is not negligible. Treatment of ZK‐5 zeolite with tetramethoxysilane deactivates the outer surface of the crystallite and increases the shape‐selectivity of the ZK‐5 zeolite with rgard to the amination reaction. Computer simulation of the zeolite skeleton in conjuction with investigations of the reaction leads to some conclusions with respect to the reaction mechanisms and