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A string of niobium-iron composite oxides with varying Nb/Fe ratios and calcination temperatures were produced and utilized to remove mixed contaminants (500 ppmv chlorobenzene and 500 ppmv toluene in air), and the structure/texture of catalytic materials were systematically characterized. The findings of the structure-performance study revealed that the physicochemical qualities of Nb 2 O 5 -Fe 2 O 3 were greatly enhanced than pure metal oxide. The presence of iron oxide hindered the crystallization of niobium oxide, which aided in the uniform dispersion of niobium-iron components into each other. Forming FeNbO 4 at Nb/Fe molar ratio of 1/2 effectively improved the thermal stability of catalyst, withstood short-time thermal shock below 850 °C. The formation of niobium-iron composite oxides improved the specific surface area, optimized the pore size distribution, increased surface acid centers, enhanced reduction/oxidation cycle, and promoted metal-metal interaction for the Nb-Fe-O catalysts. At 320 °C, the catalytic degradation efficiency of 1Nb2Fe-500 could approach 90% for chlorobenzene and 85% for toluene, and it could sustain this efficiency for at least 80 h without evident deactivation, with a high CO 2 selectivity of 86%. Furthermore, the Nb-Fe-O catalysts met the environmentally benign and low-cost requirements for environmental catalysis. [Display omitted] • The Nb-Fe composite oxides were synthesized and structure/texture were characterized. • The formation of FeNbO 4 was an important factor affecting the catalyst activity. • 1Nb2Fe-500 exhibited high performance for eliminating mixture of C 6 H 5 Cl and C 6 H 5 CH 3. • The 1Nb2Fe-500 catalyst could withstand thermal shock below 800 °C. [ABSTRACT FROM AUTHOR]