In this paper, mass transfer at the fluid-porous medium boundaries is studied. The problem considers both diffusive and convective transport, along with adsorption and reaction effects in the porous medium. The result is a mass flux jump condition that is expressed in terms of effective transport coefficients. Such coefficients (a total dispersion tensor and effective reaction and adsorption coefficients) may be computed from the solution of the corresponding closure problem here stated and solved as a function of the Peclet number (Pe), the porosity and a local Thiele modulus. For the case of negligible convective transport (i.e., Pe << 1), the closure problem reduces to the one recently solved by the authors for diffusion and reaction between a fluid and a microporous medium.