Vapour phase alkylation of aniline with ethanol is studied over a series of H-ZSM-5 zeolites containing SiO2/Al2O3 ratios of 30, 50, 70, 150 and 280. The influence of feed rate, temperature and pressure on activity and selectivity of the products, namely N-ethylaniline and N,N’-diethylaniline are investigated. The effect of acidity and SiO2/Al2O3 ratio of H-ZSM-5 on alkylation activity is discussed. H-ZSM-5 with a SiO2/Al2O3 ratio of 70 seems to have the acid sites required for optimum aniline alkylation activity and selectivity of the products.