Ozone concentrations of an electrochemical concentration cell (ECC) ozonesonde determined using a data processing equation typically lag changes in the concentrations of ozone sampled into an ECC by 20–40 s. This work develops a new equation for determining ozone concentrations of an ECC ozonesonde so that the determined ozone concentrations can respond relatively quickly to changes in the concentrations of the ozone sampled into the ECC. The new equation is derived by examining the chemical reaction rates and transport limits of related species and electrons in an ECC. To demonstrate the power of the new equation, an ECC is exposed to prescribed variations of ozone concentrations. The variations of the ozone concentrations of an ECC that are determined using both the new and the old equations are compared to the prescribed ozone variations. The results demonstrate that the ozone concentrations that are determined using the new equation responds approximately 50% faster to the prescribed ozone variations than do those obtained using the old equation.