It has been known for more than a century that the interfacial tension of mercury dipped in electrolyte solutions changes with applied potential following a near parabolic course known as the electrocapillary curve. Solution components which are adsorbable on mercury produce asymmetric curves with respect to the potential at the electrocapillary maximum. A simple mathematical description of this asymmetry has, to date, excited and eluded many scientists. Here, a simple new linear relation which describes the electrocapillary curves for the existing data has been shown for the first time. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.