A new form of a capillary potential/temperature formulation of heat and mass transfer in unsaturated soil is presented. Moisture transfer in both the vapor and liquid phases and heat transfer by means of conduction and latent heat of vaporization effects are accommodated in a one‐dimensional approach. A numerical solution of the complete formulation is then developed, based on the use of the finite‐element method, to describe spatial variations and a finite‐difference time‐stepping scheme to model transient behavior. The application of the model is then presented, making use of material parameters that have been independently established for all the soil properties specified in the formulation. A comprehensive, consistent approach is therefore claimed to be proposed. The results obtained are shown to be qualitatively correct throughout, conforming with physically realistic behavior. For a number of aspects of the work, it proved possible to examine precisely the validity of the results achieved, and in all those cases the model was found to be valid. Comparisons of the solutions with those obtained from other numerical approaches yield excellent correlations.