Abstract: The present invention provides an apparatus and method to combinatorially screen a plurality of electrochemical material compositions for use in an electrochemical cell such as a fuel cell, battery or electro-catalytic cell. The apparatus includes an electrochemical cell with one or more windows, sealed with an infrared (IR) transparent material for direct thermal imaging of an internal electrode, an electronic load for applying a voltage or current to the electrochemical cell, and a device, external to the cell, for monitoring the relative temperature of the internal electrode through each window of the cell when the load is applied. When a load is applied to the cell, the temperature observed through each window may be used as a relative measure of the electrochemical efficiency of the discreet region of the electrode being viewed and of the material compositions contained therein. The electrochemical cell may comprise discreet compositions of electrode materials.