A semi-empirical model for pool boiling over porous surfaces is presented. The pressure drop across the porous surface is estimated using Darcy's law. The significance of the latent heat flux contribution for highly porous surfaces is examined. Two nucleation factors are defined and correlated in terms of measurable quantities using literature data. An expression for the total heat flux in terms of the wall superheat, pore geometry and the physical properties of the liquid is presented. The present model matches well with literature data on pool boiling over porous surfaces, both flat surfaces and tubes from four different sources, thus validating the present approach.