External mesoporous γ-Al 2 O 3 nanorods with an aspect ratio of 2–4 has been hydrothermally synthesized using Al(NO 3 ) 3 ·9H 2 O as precursor and (NH 4 ) 2 CO 3 as precipitant without any templates and followed by a calcination step. The obtained samples were characterized by thermogravimetric analysis (TG), X-ray powder diffraction (XRD), nitrogen sorption, Fourier transform infrared spectrometry (FT-IR), and scanning transmission electron microscopy (STEM). It can be confirmed that the morphology of nanorods is formed in the low-temperature hydrothermal process of 100°C. Through the thermal decomposition of intermediate product NH 4 Al(OH) 2 CO 3 , the prepared γ-Al 2 O 3 possesses abundant external mesopores, which can act as “holders” to stabilize or anchor gold nanoparticles efficiently. Using CO oxidation as an probe reaction, the results demonstrated that Au catalyst exhibited excellent catalytic performance with the complete CO conversion at 18°C (T 50% =−11.2°C) and reactive stability over 166h under a space rate of 134,000mLh − 1 g cat −1 .