Direct numerical simulation of film boiling in a planar liquid jet is performed by solving the conservation equations of mass, momentum and energy in the liquid, vapor and air phases. The liquid–air and liquid–vapor interfaces are tracked by a sharp-interface level-set method, which is modified to include the effect of phase change at the liquid–vapor interface. An analytical model to predict the vapor film thickness and wall heat flux in the stagnation region is also developed by simplifying the momentum and energy equations in the liquid and vapor phases. The computational results show a stable vapor film formation on the wall. The effects of jet subcooling, jet velocity, and wall temperature on the vapor film thickness and boiling heat transfer are investigated.