The problem of condensation by mixed convection in a vertical channel was numerically analyzed for an air-water system. One of the channel plates was subjected to uniform heat flux and wetted by a water film flowing down. The second plate was dry and isothermal. The effects of the ambient conditions and inlet liquid parameters (inlet liquid mass flow and temperature) on the condensation process were investigated. It was observed that increasing the amount of the water film or reducing its inlet temperature benefits the condensation process.