an electrochemical cell assembly including a plurality of testing cells , a reference cell , and fluid connections between the testing cells and the reference cell . each of the testing cells includes a working electrode , which is a rotating disk or ring - disk electrode , and a counter electrode . a chemical composition , whose intrinsic kinetic properties under defined mass - transfer are to be investigated , is deposited on the working electrode . the reference cell holds a reference electrode that serves as a common reference electrode for each of the testing cells . the assembly permits simultaneous testing of many chemical compositions under identical environment .