Lepidocrocite (γ-FeOOH) microtubes with scroll morphology prepared by gas–solution interface technique (GSIT) have been modified by silver nanoparticles (Ag NPs). The successive ionic layer deposition (SILD) was first used for the synthesis of the Ag NPs on the lower surface of a solid film freely lying on the surface of a solution. The sizes of Ag NPs are about 15 nm after one synthesis cycle, and their diameters reach 35 nm after three SILD cycles. As a result of vacuum-drying, the modified film is transformed into microtubes with a diameter of about 10 μm and a length of 150 μm in such a way that the inner surface of the microtube is modified by Ag NPs. The catalytic properties of the microtubes have been observed by the decomposition of H2O2 in aqueous solution. The Ag/FeOOH microtubes move in hydrogen peroxide solutions with an average speed of 117 μm/s. This result is based on the synergetic effect between lepidocrocite nanosheets and Ag NPs, which results in the modified microtubes having enhanced mobility.