Martin's equation, Delta(g)(sln)G = Y(sin)(g)G(0) + Z delta(g)(sln)G, is extended to cover vaporization free energy (Delta(g)(1)G). The extended equation is further expanded in terms of enthalpy and entropy and then used to correlate vaporization enthalpy (Delta H-g(1)) and enthalpy of transfer from solution to gas (Delta H-g(sln)). Data available in the literatures are used to validate and support the speculations derived from the proposed equation. (C) 2007 Elsevier Ltd. All rights reserved.