Simple, sensitive, and fast sensors can be constructed from standard atomic force microscopy cantilevers. For use in liquid environments, it is preferable to use changes in surface stress as the measurement basis of the sensor. We have constructed such a sensor in an electrochemical cell so that simultaneous cyclic voltammograms and strain measurements can be made. This is demonstrated with examples of underpotential deposition of Pb on Au(lll) and electrocapillary effects in KCl.