Direct numerical simulations were used to investigate turbulence structure and scalar transfer across a shear-free, nonwavy gas-liquid interface (free surface) in stably stratified turbulent flows. These simulations solve the Navier-Stokes and thermal-energy conservation equations, using a finite difference approximation. The relation between the turbulence structure in the stably stratified turbulent boundary layer and organized motion near the free surface are discussed. In addition scalar transfer across a free surface is investigated by solving a passive scalar conservation equation after both velocity and temperature fields are fully developed The effects of stable stratification on the scalar transfer process in a region very close to the free surface are also discussed.