Recently, the application of magnesium-based gasochromic switchable mirror has been baffled by the low optical dynamic range due to the insufficient conversion between Mg and MgH2. Based on the excellent catalytic property of Nb2O5 for the magnesium-hydrogen reaction, we fabricated fluorocarbon (FC)/Pd/Mg-Nb2O5 switchable films via magnetron sputtering and low-temperature inductively coupled plasma chemical vapor deposition technologies in this study, and the optical performance and microstructure of the films were investigated. The results show that the FC/Pd/Mg-3 mol% Nb2O5 film exhibits the higher dynamic ranges of the luminous (49.4%) and solar transmittance (54.7%), compared with most of reported Mg-based alloys and Mg-TiO2 systems. The addition of Nb2O5 and covering a FC layer on the Pd/Mg film could effectively accelerate the switching response and improve such optical properties as transmittance at transparent state and dynamic range. The microstructural analysis reveals that the Nb2O5 and appropriate amount of ternary Mg-Nb-O phase in the Mg-based layer are supposed to facilitate rapid and sufficient hydrogen absorption and desorption. Furthermore, the high-valence Nb ions scattering around Mg atoms may act as a transfer station for catalyzing the reversible reaction between Mg and H. The excellent optical modulation performance and enhanced hydrophobicity of the FC/Pd/Mg-Nb2O5 films signify an application prospect for gasochromic switchable mirror. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.