The mass-transfer coefficient in the neighborhood of a row of jets entering a cross flow is determined by measuring the local sublimation rate from a naphthalene surface. This mass transfer relates directly to the heat transfer that would occur on a film-cooled wall. The experiments indicate that jets significantly increase the transfer coefficient in the neighborhood of the holes through which the jets emanate—in particular, immediately adjacent to the holes and also some distance downstream of the centerlines of the holes.