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This work aims to provide a detailed analysis of the heat transfer in direct contact membrane distillation (DCMD). The influence of mass transfer on heat transfer flux was identified in the feed thermal boundary layer, across the membrane and through the permeate thermal boundary layer. A mathematical model was proposed to evaluate the experimental values of the thermal boundary layers’ heat transfer coefficients, the membrane/liquid interface temperatures, the temperature polarization coefficient, the membrane mass transfer coefficient and the evaporation efficiency. This model was solved numerically using MATLAB® and it is based on direct experimental observations of the feed solution inlet/outlet temperatures and the mass fluxes. The obtained results showed that the mass transfer contribution to the overall heat transferred was significant only in the membrane region while it was negligible in both feed …