A steady-state, two-dimensional model for cocurrent gas and liquid flow in a trickle-bed reactor is described. The model includes gas-liquid interaction and isothermal, incompressible flow without phase change or chemical reaction. The momentum equation proposed by Saez and Carbonell is used, along with their expressions for relative permeabilities of gas and liquid phases. Capillary pressure equations determine the difference in the pressures of flowing phases. The results of the model simulation agree with experimental data on flow distribution, liquid spreading, and phase segregation in a two-dimensional trickle bed with air-water flow in both low- and high-interaction flow regimes.