Polymeric mesoporous carbon graphitic nitrides (mpg-C3N4) and ordered mesoporous graphitic carbon nitrides (ompg-C3N4) with different surface area and morphology were used to prepare palladium catalysts (Pd@C3N4) by an easy ultrasonic-assisted method. These catalysts demonstrated excellent activity and selectivity for hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline under mild temperature (30-50 degrees C) and H-2 pressure (1 bar). Pd@ompg-C3N4(r = 2.5) showed the best catalytic performance and both the activity and selectivity could be maintained for at least six reaction runs. The introduction of ordered cylindrical mesoporous structure and high concentration of surface Pd-0 (about 70%) contribute to the high reaction activity and selectivity over Pd@lompg-C3N4 catalysts. (c) 2012 Elsevier Inc. All rights reserved.