Analytical expressions have been derived for the functions Xi(o) and H-o which arise in the description of the diffuse double layer using a generalized mean spherical approximation (GMSA). The analytical expressions are shown to provide a very good alternate method to estimate Xi(o)and H-o which were calculated on the basis of numerical evaluation of integrals in previous work. They are valid in the limit of small electrical fields, a region in which the GMSA itself is valid. The GMSA results are compared to data obtained in Monte Carlo simulations carried out at the primitive level as a function of ion size and concentration for a 1-1 electrolyte. (C) 2003 Elsevier Science B.V. All rights reserved.