Triboelectrification due to frictional contact between particle and wall is prevalent in gas-solid systems. However, mechanisms of triboelectrification are not fully understood, such as the difference in the charge generation between the sliding and rolling contact. In this study, a dynamic model for the sliding and rolling electrification was developed based on the continuous condenser model. Results show that the triboelectric charge of the cylinder rolling on its round surface is larger than that of the cylinder sliding on its bottom base. Also, we proposed the triboelectric coefficient to characterize the tribocharging process. The triboelectric coefficient was an essential characteristic involved the re-charging process and the discharging process. The rolling electrification of the sphere shows a smaller triboelectric coefficient than that of the sliding electrification due to the small contact area. To shed light on the vital significance of the triboelectric coefficient, we define a dimensionless triboelectric charge to area ratio to represent the ratio of the incremental charge to the maximum triboelectric charge. (C) 2018 Elsevier B.V. All rights reserved.