The catalytic hydrogasification of coal char was investigated in a high-pressure fixed-bed tube reactor using CaO, CaCO3, Na2CO3, and K2CO3 as catalysts. Experimental results showed that the char reactivity could be greatly improved with the addition of catalysts. Analysis of char structural evolution was performed to further explore the catalytic mechanism by employing Raman spectroscopy and scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX). The results revealed that CaO catalyst inhibited the aromatic ring condensation of the char structure during hydrogasification. The catalytic reaction of CaO only occurred on the char surface. Na2CO3 or K2CO3 was reduced to metallic Na or K and diffused into the char under hydrogen atmosphere, enhancing the cracking of large aromatic ring systems into small ones, which were the active species for hydrogasification. The catalytic reaction of alkali catalyst occurred simultaneously on the surface of and inside the char. Therefore, the Na2CO3 and K2CO3 displayed higher catalytic activities than CaO in hydrogasification. (C) 2016 Elsevier Ltd. All rights reserved.