Cyclic voltammetry (CV) has been performed on light-emitting electrochemical cells (LECs) using poly(3-octylthiophene) (P3OT) as the active luminescent polymer. Above the threshold voltage, current in an LEC consists of ionic and electronic components. A purely ionic (negative) component is clearly discernible in the return scan of the CV below threshold when, as a result of the relaxation of the p-n junction, the electronic current becomes negligible. Analysis of the peak negative current reveals that LECs exhibit a mixture of thin film and diffusion controlled current behavior. Weak orange light emission is observed with an onset above 2 V.