This paper, the third in our sequence on a model geothermal brine based on a H2O-NaCl system, proposes correlations for the thermodynamic properties of specific enthalpy and dynamic viscosity of brine. It follows a similar pattern to the second paper on the density correlations, that is formulae which closely approximate the specific enthalpy and dynamic viscosity are given in terms of the primary variables T (temperature), p (pressure) and X (mass fraction of sodium chloride). These correlations cover the entire T-p-X state-space and together with the density correlations, can be used in subroutines suitable for use in numerical simulation programs.