The excess free energy per unit area of an uncharged curved interface separating a phase with a low dielectric constant from a solution containing electrolyte is considered. The contribution due to the electrolyte to the excess free energy per unit area is expanded in the curvature, and the coefficient of the linear term or spontaneous curvature is calculated. Its sign implies a tendency for an interface to curve toward the nonaqueous phase. The zeroth order term in this expansion is an earlier result obtained by Onsager and Samaras. The expansion parameter is the curvature times the Debye screening length. The opposite regime of large curvature will also be considered. To obtain these results the Gibbs adsorption equation has been used. (C) 1997 American Institute of Physics.