Abstract: A silicalite/activated carbon fiber (ACF) composite was prepared by a two-step method, in which nitric acid oxidation was used to incorporate hydrophilic groups to improve crystal seed impregnation and a hydrothermal process was used to grow silicalite on the ACFs. The samples were characterized by SEM, XRD and N₂ adsorption. Results showed that the surface of the ACFs was covered with a silicalite layer, and the specific surface area, pore volume and average pore size of the composite were 826 m²·g^-1, 0.42 cm³·g^-1 and 0.64 nm, respectively. The catalytic activity of the ACFs for NO oxidation to NO₂ was higher than that of a composite loaded with 10 wt% silicalite under dry conditions. However, the latter had a much better resistance to vapor and exhibited a more stable catalytic activity than the ACFs under moist conditions.