Sphere collision with the presence of liquid is common in industrial fluidization-based processes. A detailed understanding on its mechanics is helpful for optimizing these processes. There have been some studies regarding energy dissipation in terms of restitution coefficients. However, studies on rotational characteristics of spheres after impact are scarce. In this work, experiments are conducted to trace Al2O3 spheres obliquely impacting on a surface covered by liquid layers. Strong rotation can be observed when the sphere rebounds after the impact. The effects of tangential velocity, liquid viscosity and layer thickness on the angular velocity of spheres (omega) were investigated. It is found that omega decreases with increasing liquid layer thickness and viscosity, while increases with the tangential velocity. Furthermore, the quantitative relation of angular velocity to these impact parameters was analyzed by using a modified Stokes number (St(N)). Finally, two characteristic parameters, rotational restitution coefficient (beta) and friction coefficient (mu(f)), were calculated to distinguish rolling and sliding regions during contact (C) 2014 Elsevier B.V. All rights reserved.