This article describes an undergraduate laboratory for an instrumental analysis course that integrates electroanalytical chemistry and infrared spectroscopy. Modified electrode surfaces are prepared by constant potentiometric electrolysis over the potential range of 1.5-1.8 V and analyzed by cyclic voltammetry and infrared spectroscopy. The students learned how to prepare a poly(2,2'-bithiophene)-modified platinum sensor electrode for the detection of catechol in the presence of ascorbic acid. The peak separation in the cyclic voltammograms and the shifts of the IR peaks are used to assess the quality of the modified electrode. (Contains 1 figure and 2 tables.)