A coalescence model that incorporates both capillary and viscous contributions of the liquid binder, along with the liquid bridge volume effects, has been developed. The objective is to predict the coalescence of two spherical particles coated with a thin liquid film approaching with equal initial velocities from opposite directions. The model is based on an overall coefficient of restitution that is determined with the aid of the approximate analytical values of the maximum possible energy dissipation and a critical value that depends on the total initial kinetic energy of particles. The maximum possible energy dissipation accounts for the energy loss due to the viscous and capillary effects and inelastic collision. The proposed simplified method to determine the critical velocity has been compared with the numerical solution of the general equation of motion, and an excellent agreement has been found. The coalescence model has been investigated at the limiting conditions by neglecting either the capillary effect or the viscous effect, respectively. Finally, comparisons have been made with experimental data, and a reasonable agreement has been found. (C) 2009 Elsevier Ltd. All rights reserved.